Vietnamese IELTS learners’ perceptions of IELTS Writing Task 2 and their performance-based lexical resource

Abstract

This study explored how Vietnamese IELTS learners perceived IELTS Writing Task 2, particularly their lexical self-efficacy, and how they displayed their lexical resource in their IELTS Task 2 writing performance in four dimensions: lexical density, lexical sophistication, lexical variation, and lexical accuracy.

Data were collected from numerous IELTS classes in a city in central Vietnam. In total, 200 IELTS learners completed a questionnaire about their perceptions of the IELTS test, IELTS Writing Task 2, and their lexical self-efficacy. Eighty-six of them wrote two IELTS Writing Task 2 essays in their normal IELTS classroom hours on ready-made paper sheets in 50 minutes; Essay 1 was about the topic of living overseas and Essay 2 about community work. The time interval between the essays was one week and in counterbalanced design. The collected written scripts were analysed for:

1. lexical density, lexical diversity and lexical sophistication using 26 measures derived from the same computational system Lexical Complexity Analyzer (LCA) (Lu, 2012),
2. their relationship with the quality of the writing performance as graded by the IELTS examiners arranged by IDP IELTS
3. lexical accuracy (lexical errors), and the link between erroneous use and the IELTS Writing Task 2 performance.

The questionnaire findings show that learners were motivated to learn IELTS for differen reasons, (e.g., enhancing general language proficiency, getting ideal jobs and seeking foreign scholarships), and for its accessibility and credibility. They reported topic unfamiliarity was a major inhibiting task-related factor, and writing with appropriate and varied vocabulary was linguistically challenging for them, and so was lexical cohesion. The learners also identified different sources of anxiety involved in writing IELTS Task 2, of which self-oriented anxiety about time pressure and the performance quality was most intense. Notable was their reported confidence in using different parts of speech of lexical words, though their perceived self-efficacy was particularly low with regards to spelling lexical words correctly, and using low frequency words in their writing. Learners’ perceptions of their ability to vary their lexical use through on-topic words, synonyms antonyms and specific words for a general concept were mixed with different levels of self-efficacy. No significant correlations were found between perceived anxiety and writing performance, yet lexical self-efficacy had a significant weak correlation with the writing performance.

With regards to performance-based lexical resource, the study found an effect for the writing tasks/topics on the quantitative measures of lexical richness and their relationship with the writing performance graded by IELTS raters. Generally, the writing task about community work elicited denser, more sophisticated and more varied vocabulary than writing about living overseas. However, task influence was subject to the particular indices used to measure lexical sophistication and lexical variation. The findings also revealed that lexical variation was more strongly correlated with the writing performance than lexical density and lexical sophistication. Learners reported the latter topic was more challenging, even though there was no significant difference in the band scores between the two essays. The learners perceived the difficulty of the writing tasks in terms of topic novelty or familiarity that restricted or facilitated access to ideas and vocabulary to write.

The Vietnamese IELTS learners in the present study also committed lexical errors of different types, of which misspellings, misuse of verb forms, collocations, noun inflections and word choice were most common in both essays. The writing tasks topics did not have an effect on major error types except misspellings of general words. Lexical errors correlated negatively with the writing performance, and the correlations were weak to moderate.

The study offers important implications for IELTS, IELTS teachers and IELTS learners and for future research with regards to how to prepare learners for IELTS Writing Task 2 and how to measure lexical resource/richness.

1 Introduction

1.1 Research motivation

IELTS (International English Language Testing System) has been recognised as a reliable measure of English language proficiency trusted by thousands of organisations worldwide for its “quality and integrity” (IELTS, 2021a). Given its “prestige” influence, a large number of learners of different first language (L1) backgrounds study it for their varied individual purposes (IELTS, 2021b). The IELTS “fever” has turned unprecedentedly acute now that it can be now employed as a passport for admission into top universities in Vietnam (Phapluat, 2022; Vietnamnet, 2021). This importance of the IELTS test warrants research to understand Vietnamese IELTS learners in different contexts, their IELTS perceptions and performance in order to benefit IELTS learners / test-takers, IELTS teachers and IELTS organisers.

While Vietnamese learners of IELTS are among the most numerous IELTS learner groups in the world (Test-Taker Performance [TTP], 2017), not much is known about them in IELTS research. Lacking is empirical knowledge about their perceptions of IELTS Writing Task 2 and their performance-based lexical resource, one core component of the IELTS Writing Task 2 scoring rubric. The present study therefore explored how Vietnamese IELTS learners perceived IELTS Writing Task 2 and how they displayed their lexical resource in Task 2 writing. The focus on writing was motivated by the IELTS performance statistics that showed that the average writing band scores for Vietnamese IELTS learners have been recorded as the lowest of the four skills (TTP, 2017).

Writing is a complex meaning-making process which “converts our thoughts and ideas into text, a process that requires the purposeful choice and use of words” (González, 2017, p. 1). This underscores the importance of vocabulary to encode intended meanings, as Engber (1995) contended, “lexicon is a significant component in both the construction and interpretation of meaningful text” (p. 141). Lexical richness is a multi-dimensional construct, operationalised in four main dimensions, namely lexical density, lexical variation or diversity, lexical sophistication, and lexical accuracy (Read, 2000). Although a large body of research on L2 writing has explored one or some of these lexical dimensions, it has been largely quantitative, reporting the lexical features in different writing genres (e.g., Li, 2000; Park, 2013), or topics (e.g., Ryoo, 2018; Yu, 2010; Zheng, 2016), and/or focusing on the link between different lexical dimensions and the writing quality (e.g., Crossley & McNamara, 2012; Engber, 1995; Gebril & Plakans, 2016; Mazgutova & Kormos, 2015; Olinghouse & Wilson, 2013; Paquot, 2019).

Lexical resource is also specified as one of the core criteria in the IELTS Writing Task 2 scoring rubric, with multiple descriptors such as lexical range, lexical sophistication (use of rare/uncommon lexical items) and lexical accuracy (errors) (IELTS, 2021b). Some recent research on IELTS writing, though varied in its foci, has addressed the different variables that might impact the quality of IELTS writing performances such as test-takers’ first language (L1) background and/or proficiency (Banerjee, Franceschina & Smith, 2007; Barkaoui, 2013; Riazi & Knox, 2013). No IELTS research has explored IELTS learners’ perceptions of their own lexical efficacy and analysed all four lexical dimensions of their IELTS Writing Task 2 performance (lexical density, sophistication, variation, and lexical accuracy) as learners wrote IELTS Task 2 essays about different topics in their normal IELTS classes.

1.2 The present study

The present research was designed in two main parts. Part 1 aimed to understand Vietnamese IELTS learners’ perceptions of the factors influencing their IELTS Task 2 writing and their lexical self-efficacy. Part 2 focused on analysing the lexical resource of their IELTS Writing Task 2 performance in four dimensions: lexical density, lexical sophistication, lexical variation, and lexical accuracy in performances in two different topics. The first three lexical dimensions were analysed quantitatively using a large set of measures facilitated by the computational system, named Lexical Complexity Analyzer (LCA) (Lu, 2012). The last lexical dimension was examined in an exploratory qualitative manner to identify the lexical errors that Vietnamese IELTS learners committed in their IELTS Task 2 writing and their relationship with writing performance.

1.3 Research questions

The research sought to answer the following research questions.

The findings offer important pedagogical implications for IELTS teachers and Vietnamese IELTS learners as to how to guide preparations for IELTS Writing Task 2, and to enhance productive lexical knowledge (lexical resource) in Writing Task 2. The study also has useful recommendations for IELTS, IELTS teachers, learners and researchers.

2 Literature review

Writing in another language rather than one’s mother tongue (L2) is a form of pushed output (Swain, 2005) where learners stretch their linguistic repertoire to convey intended messages. In writing, “the cognitive window is open somewhat wider and learners have a richer opportunity to test their hypotheses when they write than when they speak” (Williams, 2012, p. 328). Writing is indeed a complex process of meaning-making and problem-solving (González, 2017) which involves not only linguistic competence but also other competences in order to produce a piece of written text. And as such, writing performance is often rated on a number of aspects. For example, IELTS Writing Task 2 performance is rated in terms of task response, lexical resource, coherence/cohesion, and grammatical range and accuracy (IELTS, 2021b). The act of writing a text or an essay in an L2 could be challenging for many learners, and even more taxing in high-stakes writing tests such as IELTS.

The literature review is structured into two main sections corresponding with the two major parts of the study design. The first section discusses learners’ perceptions of IELTS Writing Task 2 and lexical self-efficacy and reviews related research. The second section focuses on performance-based lexical resource, presenting quantitative lexical measures of lexical density, lexical sophistication and lexical variation followed by related studies. It then addresses the importance of lexical errors and reviews relevant research.

2.1 Learners’ perceptions of IELTS Writing Task 2 and lexical self-efficacy

2.1.1 Learners’ motivation to study IELTS

Understanding the motivation that underlies learners/test-takers learning and taking the IELTS test is important for test preparation and test use. Some studies have documented different reasons why individuals learn and take the IELTS test, though they differ in scope and focus. For example, in a study on the perceptions of students and staff on IELTS, Coleman, Starfield, and Hagan (2003) identified three primary reasons for IELTS learning in tertiary settings in Australia, the UK, and China: i) to get admitted to favourite universities; ii) to increase chances of university admission; and iii) to improve English in general. Chapelle, Yates and Benson (2019) focused on understanding how test-takers prepared for the IELTS test by surveying 679 IELTS test-takers in Australia who originally came from 80 different countries. Their findings show a different trend of motivation with half of the test-takers taking the test mainly for immigrating to Australia or seeking permanent residency there. About a quarter did so to pursue a study course and nearly 16% to obtain a professional qualification. This line of research on students’ views was conducted in the host countries, which might be very different from IELTS learning motivation in home countries.

Research on learners’ driving force to study IELTS in their home countries is limited. One such study was conducted in Iran by Sari and Mualimin (2021), finding that a large majority (80%) of the IELTS learners in their study reported learning IELTS to seek foreign scholarships. More research is needed to understand learners’ motivation to study IELTS.

2.1.2 Potential factors affecting writing performance

There are a number of factors theorised to affect a written text and these features fall into three groups: task-inherent features, task conditions and learner variables (e.g., proficiency, motivation) (Robinson, 2001, 2011). Task topic is among task design features that might elicit different linguistic exhibitions in writing performance. It is theorised from the perspective of task complexity (Robinson, 2001, 2011; Skehan, 1998) that less familiar topics are more conceptually challenging and will induce lower linguistic complexity and accuracy than known topics. Topic familiarity means “how much knowledge and/or experience learners have about a given topic” (Yang & Kim, 2020, p. 4) and a lack of topical knowledge could be a potential factor that impacts lexical use (Coxhead, 2018, p. 1). Some research has shown an effect of topic on the linguistic features of the writing performance (e.g., Ryoo, 2018; Yoon, 2017; Yu, 2010) (further see Section 2.2).

Task conditions refer to the conditions in which learners write their texts. Whether or not it is a timed performance, or whether planning time and additional materials (other than task prompts) are allowed could potentially affect the quality of task performance. For example, given time to plan one’s task performance will ease the conceptual burden, so that learners could have more attentional resources to attend to linguistic aspects of the performance (Skehan, 1998, 2016).

Learners are key players in the process of writing, and learner-inherent factors such as their language proficiency, task motivation, anxiety, experience, and L1 backgrounds are further influencers (Robinson, 2001, 2011). Given the potential roles of these individual factors, it is important to understand the factors learners themselves identify as barriers in writing. As vocabulary carries most meaning (Schmidt, 2001), it is therefore an integral means to the process of text composing in free independent writing tasks such as IELTS Writing Task 2. It is important to understand how confident learners are in using vocabulary in writing (lexical self-efficacy) in order to plan appropriate instruction to develop writing proficiency.

2.1.3 Writing self-efficacy and lexical self-efficacy

Self-efficacy is a term viewed from the lens of social cognitive theory as “people’s judgment of their capabilities to organize and execute courses of action required to attain designated types of performance” (Bandura, 1986, p. 391). Delcourt and Kinzie (1993) contend that “perceived self-efficacy reflects an individual’s confidence in his or her ability to perform the behaviour required to produce specific outcomes” (p. 36). With regards to the skill of writing, writing self-efficacy is accordingly regarded as learners’ own judgement of their abilities to write. It is operationalised in three major components: linguistic self-efficacy, performance self-efficacy and self-regulatory self-efficacy (see Teng, Sun & Xu, 2017). The first involves the learners’ ability to use the different aspects of the language such as lexis, syntax, discourse and rhetorical styles to produce a piece of written text. It refers to “individuals’ self-judgment of their capability to retrieve words from their long-term memory, to use appropriate syntax to express ideas, and to follow discourse requirements for the production of composing” (Teng et al., 2017, p. 10). The second component, performance self-efficacy, is about learners’ self-evaluation of their capabilities to complete a given classroom task, which will provide useful insights into learners’ level of confidence in performance that could inform teachers to plan their writing teaching. The third dimension, self-regulatory self-efficacy, addresses the self-regulating process involved in writing, how learners self-regulate, take control and problem-solve in the writing process. The present study focused on linguistic self-efficacy and in particular, it aimed to understand Vietnamese IELTS learners’ own judgement of their abilities to use lexical items in writing IELTS Writing Task 2.

Lexical self-efficacy was defined in the present research as learners’ beliefs about their capabilities (what they can do) to demonstrate productive lexical knowledge in writing, based on the seminal framework of Nation (2013) about what is involved in knowing a word. This framework is “the most comprehensive framework of vocabulary knowledge in second language (L2) studies to date” (Godfroid, 2020, p. 434).

The conceptualisation of lexical word knowledge in Nation’s (2013) framework postulates that knowing a word entails not only knowing its form, but also its meaning and its use from both receptive and productive perspectives. Table 1 presents this framework in its productive aspect, as the present study focused on productive lexical knowledge in writing. This framework guided the development of the questionnaire items in the first part of the present study, in ‘can do’ statements to explore Vietnamese IELTS learners’ perceptions of their lexical self-efficacy in writing. It was further informed by the descriptors of lexical resource delineated in the IELTS Writing Task 2 scoring rubric (IELTS, 2021b), which takes into account: i) how wide test-takers’ lexical range is; ii) how sophisticated their vocabulary is (i.e., use of ‘uncommon lexical items’); and iii) how accurately they use lexical items in their writing (i.e., errors) (IELTS, 2021b). In its scoring rubric, IELTS highlights the explicit link between these aspects of lexical resource and IELTS Writing Task 2 performance.

Table 1: Lexical word knowledge in written language production

Note: extracted from Nation (2013, p.27).

2.1.4 Related studies on learners’ perceptions of EFL writing/IELTS writing and lexical self-efficacy

2.1.4.1 Learners perceptions of EFL writing/IELTS writing

A number of recent studies have sought to understand EFL learners’ perceived challenges involved in writing in different contexts. By means of interviews, Peloghitis (2016) found EFL first-year university students in Japan perceived the rhetorical dimension (which involves elements of text that realise communicative functions) of the argumentative essay to be the most challenging. Derakhshan and Shirejini (2020) surveyed 120 Iranian EFL students and later interviewed 24 of them about their perceptions of the most challenging aspects in writing. They found numerous difficulties related to spelling, grammar, punctuation, word choice, idiomatic and collocational uses, rhetorical style, genre familiarity, and L1 transfer. As the students perceived, language-related difficulties were more intense than content-related ones.

Other studies have also shown greater difficulties with the linguistic aspect of the writing act. For example, Enneifer’s (2021) study revealed that spelling and grammar were reportedly the most problematic for Tunisian EFL students. In other contexts, vocabulary and grammar reportedly posed the greatest difficulty for Taiwanese students (Chen, 2002), for beginners EFL students in the Philippines (Mojica, 2010) and Indonesian EFL students (Bulqiyah, Mahbub & Nugraheni, 2021).

Limited vocabulary and insufficient grammatical knowledge were also cited as major barriers in writing argumentative essays for Vietnamese English-majored students (Lam et al., 2020). The studies discussed here suggest that grammatical and lexical challenges were common for many groups of learners.

Other non-linguistic factors have been reported in some studies. Bulqiyah et al. (2021) found Indonesian students’ writing difficulties arose from lack of practice, low writing motivation and low self-confidence. With an exclusive focus on writing anxiety, Rezaei and Jafari’s (2014) research demonstrated that EFL Iranian students recounted different sources of anxiety: worry about performance, fear of negative evaluation from the teacher, lack of confidence and limited knowledge of the target language. Focusing on Chinese university students, Wei, Zhang and Zhang (2020) investigated the relationship between students’ perceptions of writing difficulty and the rhetorical transfer from learners’ L1 Chinese to the target language, English. They found that greater perceived writing difficulty was positively correlated with the occurrences of transfer of the rhetorical style from Chinese to English. Saeli and Cheng (2019) show that Farsi EFL learners had a negative evaluation of their own L1, which affected their perceptions of EFL writing. These latter studies suggest a potential influence of L1 in writing. As writing is both a cognitive and affective process (Boscolo & Hidi, 2007), understanding persona factors such as their anxiety and L1 influence would be further telling of the challenges learners have.

Turning to IELTS writing, in a study on Japanese stakeholders’ (teachers and students) beliefs about IELTS Writing and Speaking tests through questionnaire and interview surveys, Iwashita, Sasaki, Stell, and Yucel (2021) found that their first-year university student participants judged the difficulty of IELTS Writing Task 2 to be based on the familiarity of the topic. Logical organisation of ideas and appropriate use of lexis and grammar were their additional concerns. Gardiner and Howlett (2015) researched the perceptions of 25 international students in Australia about four English proficiency tests including IELTS. The findings revealed that timing and idea generation were inhibiting for them when writing IELTS Task 2 essays. Maharani and Setyarini (2019) found that insufficient vocabulary, idea formulation, and incorrect spelling were among the difficulties reported by three Indonesian IELTS learners in their study. Other affective issues such as lack of interest, fatigue, and anxiety were added challenges. Nguyen and Nguyen (2022) surveyed 205 Vietnamese IELTS learners in two English centres in Ho Chi Minh City, Vietnam about their perceived problems related to writing IELTS Writing Task 2. Five most frequently reported problems included limited time, inability to paraphrase, lack of background knowledge, failure to connect ideas and to write clear sentences. These difficulties were reported to stem from the influence of Vietnamese L1, anxiety associated with writing and limited exposure to the target language. Misspellings and inappropriate word choice were among the least difficult aspects reported.

The learners’ self-reports in IELTS research and EFL writing have shown the different challenges associated with IELTS writing. Generally, what learners found difficult about IELTS Writing Task 2 was related to the linguistic dimension, the task topic and non-linguistic affective factors, though the level of intensity was mixed across studies.

2.1.4.2 Learners’ perceptions of lexical self-efficacy in written language production

Although numerous studies have investigated writing self-efficacy and its relationship with writing performance or learner motivation (e.g., Bruning et al., 2013; Pajares, 2003; Teng, et al., 2017), to our best knowledge, there is a scarcity of research on learners’ lexical self-efficacy per se in writing in general and in IELTS Writing Task 2 in particular. While vocabulary has been identified as one of the major obstacles in writing for many groups of learners (e.g., Chen, 2002; Lam et al., 2020; Mojica, 2010), and textual analysis of lexical errors is revealing of lexical problems learners encounter (e.g., Chan, 2010; Hemchua, & Schmitt, 2006; Llach, 2007, 2011; also see 2.2.4), the different aspects of lexical use, where learners believe they have low or high confidence, deserves research attention. Learners’ beliefs about their level of confidence to use vocabulary in writing are important in understanding their productive lexical knowledge in order to plan appropriate instruction and assistance for students.

2.2 Performance-based lexical resource

Productive lexical knowledge or lexical resource is one of the core marking criteria of IELTS Writing Task 2 performance that measures different aspects such as lexical range, use of uncommon lexical items and lexical errors (IELTS, 2021b). In its scoring rubric, IELTS highlights the explicit link between these aspects of lexical resource and highscoring IELTS writing performance.

Lexical resource is a multi-faceted construct defined by Read (2000) as involving lexical density, lexical variation or diversity, lexical sophistication, and lexical accuracy. Research has explored lexical resource in terms of lexical richness operationalised by these different lexical dimensions and how lexical richness linked to writing quality (e.g., Crossley, 2020; Gebril & Plakans, 2016; Gregori-Signes & Clavel-Arroitia, 2015; Higginbotham & Reid, 2019; Maamuujav, 2021; Zheng, 2016) or whether it is a marker of learner proficiency (e.g., Crossley, Salsbury, & McNamara, 2011; Olinghouse & Wilson, 2013), though these studies differ in the indices used to measure lexical richness.

2.2.1 Quantitative measures of lexical richness

2.2.1.1 Lexical density

Lexical density first introduced by Ure (1971) refers to the proportion of lexical words (content words) to the total number of words in a given text. And as such, it measures the amount of information content in a text and represents “the kind of complexity that is typical of written language” (Halliday, 1985, p. 62) and of academic writing (Biber & Gray, 2010, 2016).

Some research has shown mixed results about the relationship between lexical diversity and the quality of the scripts. For example, lexical density was found to closely relate to the writing quality (e.g., Jarvis, 2002; Yu, 2009), but no such relationship was observed in some other studies (e.g., Nasseri & Thompson, 2021; Uccelli et al., 2012). In other research, more proficient learners tended to write texts with a higher level of lexical density than lower proficiency learners (e.g., Gregori-Signes & Clavel-Arroitia, 2015; Kim, 2014). More research on this dimension of vocabulary use is warranted, as lexical density has been much less extensively researched than other dimensions of lexical resource/richness (Johnson, 2017).

Lu (2012) noted that although lexical words are generally the opposite open category of the closed grammatical/function words, different studies have defined lexical words in different ways, or that the definition of lexical words is not provided in many studies. This makes it challenging to compare and interpret the findings across studies. In our study, lexical words refer to nouns, adjectives, verbs (excluding modal verbs, auxiliary verbs, “be,” and “have”), and adverbs with an adjectival base, including those that can function as both an adjective and adverb (e.g., “fast”) and those formed by attaching the -ly suffix to an adjectival root (e.g., “particularly”)” (Lu, 2012, p. 192). Lexical density was computed as the proportion of the number of lexical words (N ) out of the total number of tokens (N) (Table 2).

Table 2: Lexical density and its measure

Note. N= the number of tokens, lex= lexical words

2.2.1.2 Lexical sophistication

Lexical sophistication broadly refers to the presence of sophisticated words in a text, and it is defined as “the proportion of relatively unusual or advanced words in the learner’s text” (Read, 2000, p. 203). Word frequency is “the prototypical measure of lexical sophistication” (Crossley & Kyle, 2018, p. 48). The IELTS Writing Task 2 scoring criteria (IELTS, 2021b) take into account how test-takers use “uncommon lexical items” or “less common words” in their scripts and the use of low frequency words differentiates higher and lower Writing Task 2 band scores in the scoring rubric.

In lexical research, lexical sophistication is calculated by different indices (Table 3), as described in Lu (2012, p. 192). For example, it is computed by Linnarud (1986) and Hyltenstam (1988) as the proportion of the number of sophisticated lexical words (Nslex) out of the total number of lexical words (Nlex) (LS1). However, the reference to sophisticated words in these two studies was different. In Linnarud (1986), sophisticated words were the words introduced from grade 9 onwards in the educational system of Sweden, whereas in Hyltenstam (1988), sophisticated lexical words were the words beyond the list of 7000 most high frequency words in Swedish.

Table 3: Measures of lexical sophistication

Note. adapted from Lu (2012, p. 193)

Laufer (1994) and Laufer & Nation (1995) created the Lexical Frequency Profile (LFP) to measure the size of productive lexis of L2 learners and how it was related to learner proficiency. They examined the ratio of word types in a language sample that occurred in each of the four frequency lists: i) the first 1000 most frequent words; ii) the second 1000 frequent words); iii) the academic word list; and iv) words that are not covered on these lists. In her study with university students, Laufer (1994) calculated lexical sophistication by means of the proportion of sophisticated word types (Ts) out of the total types (T) (LS2). Sophisticated words were defined as those beyond the 2000 basic words to include words in the third and fourth groups. She found a significant difference in the pre-test (entrance exam) and post-test (one semester and two semesters later) writing performance in the percentages of academic words used. Many researchers have used LFP to calculate lexical sophistication, by means of the proportion of sophisticated word types that were in the third and fourth lists out of the total number of word types (e.g., Maamuujav, 2021; Ryoo, 2018). In this way, words that are less frequent when checked against a reference corpus are considered more complex or sophisticated than more frequent words (Kyle & Crossley, 2016).

Other researchers focus on sophisticated verbs that occur in a text. As presented in Lu (2012), verb sophistication-I (VS1) was used to measure lexical sophistication in Harley and King’s (1989) study, calculated “as the ratio of the number of sophisticated verb types (Tsverb) to the total number of verbs (Nverb) in a text” (Lu, 2012, p. 192). Sophisticated verbs in their study were defined as verbs that were beyond the list of 20 or 200 most common verbs in French. They found that native and non-native writers of French differed significantly in this verb measure.

The correct version of VS1 (CVS1) (Wolfe-Quintero et al., 1998) and the squared version VS2 (Chaudron & Parker, 1990) are adapted versions to deal with the issue of sample size dependency (see Lu, 2012 for further information). Following Lu (2012), in the present study, sophisticated words were the words beyond the 2000 most frequent words in the BNC word list” (p. 197) (further see Section 3.2.3.1).

2.2.1.3 Lexical variation

Lexical variation or interchangeably lexical diversity is described as the “variety” of vocabulary in use in a text (McCarthy & Jarvis, 2007, p. 459). Different from lexical density which presents the density of information in a text, lexical diversity refers to “the range of vocabulary and avoidance of repetition” (Malvern, Richards, Chipere, & Durán, 2004, p. 3). Information about the different unique words, or the “phonologicallyorthographical different word forms” is revealing of learners’ vocabulary size (Housen et al., 2008, p. 3). IELTS has also made it explicit to the test-taker the link between a wide lexical range and a high band score in its Writing Task 2 scoring rubric (IELTS, 2021b).

Lu (2012) described the different quantitative measures of lexical variation in two broad groups: general word variation and lexical word variation. The first group is related to general words and general word types and consists of two sub-groups. Sub-group 1 includes similar measures that are based on the number of different words (NDW) or word types (i.e., types or T) used in a text (Table 4). As NDW represents the “nonrepetitive” or “unique” words in a text (Nasseri & Thompson, 2021, p. 2), it is subject to the length of the script (Malvern et al., 2004). To overcome this drawback, a number of standardised measures have been developed. One is to select a group of sub-samples of the same length from the text sample and calculate the average mean of NDW of these sub-samples. In Lu’s (2012, p. 197) description, NDW-50 refers to the NDW in the first 50 words of the script; NDW-ER50 is calculated as the mean average of the NDW of the 10 randomly selected subsamples of the script with a word length of 50 words per subsample; NDW-ES50 is the average NDW in 10 independent subsamples created from the script and each subsample is 50 consecutive words long and has a random starting point.

Table 4: Lexical variation based on the Number of Different Words (NDW)

Note. Adapted from (Lu, 2012) and Nasseri &Thompson (2021)

Subgroup 2 is about the similar measures of lexical variation based on the ratio of different word types (T) to the total number of tokens (T) of a given text, or TTR (type-token ratio) (Templin, 1957). TTR is also sensitive to the length of the text, meaning that the longer a given text is, the smaller this ratio is. Thus, TTR might not be a reliable measure when there is great text variability in length (Malvern et al., 2004). For this reason, alternative TTR-based measures of lexical variation have been developed as mathematical transformations of the traditional TTR, and they are summarised in Table 5 (see Lu, 2012 for a detailed description of these measures).

Table 5: Lexical variation based on Type-Token Ratio (TTR)

Note. T = the number of types, TTR = Type Token Ratio, N = the total number of tokens, lex = lexical items, Log = logarithm (adapted from Lu, 2012; Nasseri & Thompson, 2021)

LogTTR and Uber are two logarithm-based indices of lexical diversity. LogTTR draws on the concept that “the rate of increase of types with increasing token count will be proportional to the TTR for any given value of N” (Malvern et al., 2004, p. 27). Uber value (Dugast, 1979) was found to significantly correlate with the performance rankings of test-takers in oral narratives (Lu, 2012) and to accurately represent the lexical variation of texts (Jarvis, 2002). Vocd (D) was recommended by Malvern et al. (2004) as a viable option to overcome the issue of sensitivity of text length associated with TTR. The D index operates as a best-fitting method by randomly sampling words to create different segments of TTR and then identifying the best-fitting TTR curve for all. As Nasseri and Thompson (2021) put it, “curve fitting is a process of using a mathematical function which can fit all or a specified number of data points (e.g., on a curve) in its best possible way” (p. 4). D value was a significant predictor of language proficiency in oral narrative performance (Lu, 2012) and in written language production (Yoon, 2017).

In the second broad group, lexical word variation, different indices are calculated based on TTR of the parts of speech of the lexical words in a language sample (Table 6). Lexical word variation (LV) is computed as the proportion of lexical word types to the total number of lexical words in a script, and it has been used in numerous studies with mixed findings (see Lu, 2012). Verb variation 1 (VV1) is calculated by the proportion of verb types (different non-repetitive verbs) out of the total verbs (Harley & King, 1989). Different adapted versions of VV1 include squared VV1 (Chaudron & Parker, 1990) and corrected VV1 based on Carroll’s (1964) adapted CTTR to minimise text length sensitivity.

The last five measures in Table 6 share the same denominator, the number of lexical words. Verb variation II (VV2) is computed by the ratio of verb types to the number of lexical words. Similarly, noun variation (NV), adjective variation (AdjV), adverb variation (AdvV) and modifier variation (ModV) are calculated by the ratio of their types out of the number of lexical words in a text. According to Lu (2012), these five measures were used in McClure’s (1991, cited in Lu, 2012) study of language production by school students of English L1 and bilingual Spanish and English. Significant differences were found between the groups of students in all the measures, except verb variation.

Table 6: Lexical word variation and lexical variation based on types of word parts of speech

Note. Adapted from Lu, 2012, p. 195; N = the number of tokens, T = the number of types, lex = lexical items, adj=adjective; adv=adverb

Although research has varied in scope, and in measures of lexical diversity, general findings show that the greater the lexical diversity, the more advanced the learners proficiency, or the higher their writing scores (e.g., Crossley & McNamara, 2012; Gebril & Plakans, 2016; Malvern et al., 2004; Mazgutova & Kormos, 2015; Olinghouse & Wilson, 2013; Paquot, 2019).

2.2.1.4 Relationships between lexical measures and writing quality

Establishing relationships between lexical density, lexical sophistication and lexical variation is useful to understand the different aspects of L2 lexical resource. Some research has shown that lexical density and lexical diversity are not associated with each other in oral performance (Lu, 2012) and written language production (Nasseri & Thompson, 2021), suggesting they measure different things. A trade-off between lexical diversity and sophistication was recorded in some studies (Verspoor, Schmid, & Xu, 2012; Yoon & Polio, 2017), while there were no correlations between measures of lexical diversity and sophistication (e.g., González, 2017; Laufer, 1994). Lexical diversity has a stronger link to the quality of the writing than use of advanced words (González, 2017). Zheng (2016), among others, has observed that while lexical variation reflects learners’ proficiency, lexical sophistication might reach a ‘plateau’, and the trade-off between lexical diversity and lexical sophistication might level off when learners enter a more mature stage of language proficiency.

Some research has demonstrated that measures of lexical variation and sophistication are subject to the writing topics. With a focus on the argumentative writing that is closely relevant to IELTS Writing Task 2, Yoon’s (2017) research particularly revealed that the part-time job topic induced more complex language use than the smoking-banning topic. Yu’s (2010) findings show that scripts in impersonal and familiar topics contained more varied vocabulary (by D index) than those in personal unfamiliar topics. An impact of writing topic was found in Zheng (2016), with familiar topics inducing greater lexical variation and sophistication, even though topic was not a focus in his research. Focusing on an ESL context, He and Shi (2012) found topic familiarity had a facilitative role in idea development, and general topics elicited more academic words than specific topics. In Ryoo’s (2018) study, greater diversity measured by TTR was observed when EFL Korean learners wrote about the topic of climate change than the topic of leadership These studies have shown the potential effects of topic on language use in written compositions.

Despite the multiple existing measures of lexical variation, “there is no consensus among researchers concerning a single best measure” (Lu, 2012, p. 194). Research has tended to use one or a few of these options to measure lexical variation. Not many studies have used all the quantitative measures. By using all the measures of lexical variation described here, Lu (2012) found useful diagnostic information about lexical resource in oral narrative performances and called for similar research in written language production to further understand the complex multi-dimensional construct of lexical richness and writing quality. The present study thus employed all 26 measures used in Lu (2012) to analyse the lexical richness of IELTS Writing Task 2 performance in different tasks/topics by Vietnamese IELTS learners.

2.2.1.5 Studies on quantitative measures of lexical resource in IELTS writing

A number of studies focus on IELTS writing, its linguistic and/or discourse aspects and writing quality. For example, Banerjee, Franceschina and Smith (2007) examined the scripts of academic Writing Task 1 and Task 2 written by Chinese and Spanish L1 IELTS test-takers for the three lexical dimensions: lexical density, lexical diversity and lexical sophistication. They found that higher- scoring scripts displayed a higher level of lexical density, lexical variation measured by TTR, and lexical sophistication measured by number of uncommon words. They also reported L1 had an influence on these measures.

Riazi and Knox (2013), in their analysis of textual features of 254 Task 2 scripts from test-takers of different L1 backgrounds, found scripts with a higher band score contained more sophisticated words (more low frequency words) and more diverse words (measured by TTR). With a different focus, Barkaoui (2016) explored possible changes made of IELTS Writing Task 2 performance in repeat tasks and found that longer essays with more diverse words (MTLD value) and sophisticated words received higher rating.

The research on IELTS writing reviewed here differed in their foci, though they generally found lexica diversity has a close link with script quality, and is an indicator of writing proficiency. No research has explored all the three dimensions of lexical resource, and used a large number of measures. Given the ongoing debate and the different results obtained with the different measures used to gauge these lexical aspects, more research that combines multiple measures is warranted to better understand lexica richness as a multi-dimensional construct in L2 writing.

IELTS has been well known for its rigorous validation to ensure fairness and maintain integrity (IELTS, 2021b) and presumably, IELTS has ensured the same task difficulty across tests and tasks of the same category as it “strategically minimises the impact of topic familiarity” (Smith, 2019, p. 5). Yet, as writing in a foreign language is a complex process of making meaning, the writing topic might have potential effects on idea generation, as test-takers need to have background knowledge on a variety of topics to be successful in IELTS writing (Wilson, 2010). The present study was further interested in exploring how the lexical features were displayed in IELTS Task 2 writing of different topics.

Writing Task 2 is a free production task, i.e., it is assumed to depend on how test-takers know about the topic of the given task. Research has shown that topic has a potential effect on the linguistic traits of the writing performance (see Section 2.2.4.1). Coxhead (2018, p.1) postulated that “if a learner does not know much about a topic, then it is likely that their knowledge of the vocabulary related to that topic is also not well known”. It is thus important to understand how learners use lexical items in different IELTS Writing Task 2 topics. Research on the effect of writing topic has been limited and focused on lexical variation or sophistication. Not much research has attempted to explore multiple aspects of lexical richness. Johnson (2017) further observed that much research has focused on lexical diversity, while more research is warranted on lexical density and sophistication.

2.2.2 Lexical accuracy

2.2.2.1 Lexical accuracy in IELTS writing task 2 and its role in Second Language Acquisition (SLA)

Lexical accuracy is the fourth dimension of lexical resource, in addition to lexical density, lexical variation and lexical sophistication (Read, 2000). In its scoring rubric, IELTS (2021b) operationalises lexical accuracy in the lexical resource dimension in terms of the frequency of errors (‘rare errors’, ‘occasional errors’, ‘some errors’, ‘noticeable errors’) and type of errors (spelling, collocation, word formation) or inaccurate use of low frequency words in the descriptors throughout the band scores (p. 21).

For the lower band scores, counts of lexical errors are accompanied by whether they affect the reader’s comprehensibility or not, or whether the piece of text that contains a lexical error communicates well or not.

Lexical words might be defined differently in different studies. Generally, a lexical word is used erroneously “if it contains a malformation, if it is not an English word or if it violates native-like use in the context where it appears” (Celaya & Torras, 2001, p. 6). In other words, lexical errors are deviated forms that are not acceptable in the target language (Llach, 2011). As such, documentation of lexical errors learners committed while writing in a foreign language is important in a number of ways. Firstly, lexical errors provide useful insights into learners’ vocabulary acquisition. In Laufer’s (1991) words, “lexica errors are a reliable instrument to investigate the organisation of the mental lexicon in L2 and to find out more about vocabulary development” (p. 270). Lexical errors also inform learners of the gaps between their lexical knowledge and what they want to communicate. Through conveying written messages, learners notice these gaps, test their hypothesis and produce ‘pushed output’ (Swain, 2005). These processes are useful for lexical acquisition (Schmidt, 2001; Swain, 2005). In other words, lexical errors revea the lexical gaps of learners. Pedagogically, understanding what lexical errors learners commit, why and when they commit errors will guide teaching that helps remedy or prevent errors to improve the quality of writing (Llach, 2011). An analysis of lexical errors in IELTS Writing Task 2 performance is obviously important, given the link between lexical errors and IELTS Writing Task 2 performance band scores is explicitly stated in the scoring rubric (IELTS, 2021b). Research has shown lexical errors demonstrate the learners’ lexical competence and/or mark the quality of the written text (e.g., Engber, 1995; Laufer & Nation, 1995; Llach, 2007).

2.2.2.2 Related studies on lexical errors in ESL/EFL writing

Extensive research has examined general errors in writing in different ESL/EFL contexts. These could be broadly categorised into two groups. The first group reported descriptive types and frequency of lexical errors alongside the other types of writing errors. For example, Chan (2010) explored written errors at the morphological, lexical, syntactic and discourse levels in 689 free-writing essays of 200-300 words written by 387 Hong Kong Cantonese ESL learners of three proficiency levels. It was found that lower proficiency learners tended to commit more errors. Of the errors found, lexical errors were the second most common after syntactic errors. Words with similar forms (i.e., nearly/nearby) and near synonyms (i.e., fight/beat) accounted for an extensive ratio of lexical errors. Similarly, Phuket and Othman (2015) examined writing errors made by 40 English-major Thai university students in their narrative essays of about 300 words, which were written for one hour without dictionary access. Erroneous use of lexis was also the second most frequent after grammatical errors, of which words translated from Thai and inappropriate word choice constituted a large proportion, followed by confusion of sense and collocations.

The second group identified lexical errors as one of the writing error categories without specifying sub-types of lexical inaccuracy (e.g., Gibriel, 2020; Lee, 2020; Lahuerta, 2018; Mohammadi & Mustafa, 2020). The definition of lexical errors varied across studies, being inappropriate use of prepositions, word choice or parts of speech (Lee, 2020) or use of lexical-idioms and vocabulary (Lahuerta, 2018). As a general type of writing errors, lexical errors were reportedly the second most common type of writing errors following grammatical ones committed by Korean EFL learners (Lee, 2020). Spanish ESL learners in Lahuerta’s (2018) study also made numerous lexical and morphological errors. Likewise, referred to as word mischoice, lexical errors were one of the five common writing errors (articles, prepositions, word choice, spelling and punctuations) committed by EFL learners from Iran, Pakistan, and China in Mohammadi and Mustafa’s (2020) systematic review.

Different from the findings of the aforementioned studies, Gibriel (2020) found lexical errors, which were generally defined as inappropriate choice of English words, to be the least common errors in comparison with mechanical and grammatical ones committed in writings by 50 pre-course students majoring in Pharmacy and Engineering at an Egyptian university.

A few studies have explicitly examined learners’ lexical errors in EFL or ESL writing. Indeed, the studies that exclusively focus on lexical errors have been largely descriptive by recounting types of lexical errors that learners in different contexts committed in their writing (e.g., Ander & Yildirim, 2010; Hemchua & Schmitt, 2006; Li, 2015). For example, with a comprehensive taxonomy of 23 types of formal and semantic errors, Hemchua and Schmitt (2006) explored lexical errors made in argumentative essays of 300-350 words written by 20 Thai third-year university English majors. Semantic errors were reported to nearly double formal ones and erroneous use in near synonyms, preposition partners, suffixes, calques, and verbs were respectively found to be the most common.

Set in another EFL context in Asia with English-major university students, Li (2015) conducted a study to explore the erroneous use of lexical words and their possible causes in 62 argumentative essays of 31 Mongolian English-major students at a university in China. James’ (2001) framework was adopted to analyse the learners errors, which comprise formal errors, collocation errors and mix-up of parts of speech. He found slightly different results from Hemchua and Schmitt’s (2006) that errors in word forms accounted for more than 50% of the total lexical errors, of which misspellings and prefixes outnumbered others. Misuse of parts of speech/collocations was the next common error type.

Conducted in an EFL context in non-Asian countries, with a corpus of 53 problem solution essays written by 53 Turkish university students of elementary level, Ander and Yildirim (2010) identified 743 lexical errors, and word mischoice, misspelling and lexical word omissions were the most common errors, standing at 30%, 20% and 19% respectively. Llach (2017) reviewed previous studies on common errors found in EFL writings and concluded that misspellings were the most frequent among the seven common lexical errors: borrowings, lexical adaptation of an L1 word to L2 word, semantic confusion, calque, cognate, spelling, and construction, although she did not aim at rating the errors’ frequency.

A limited body of studies has reported the link between lexical errors, types of lexica errors and learners’ writing quality. Llach (2007, 2011) are among useful related studies on lexical errors in written language production. For example, Llach (2007) examined the impacts of lexical errors on the composition quality of 71 fourth-grade Spanish EFL learners who were asked to write a letter to a prospective English host family in 30 minutes in any length and without any reference to materials. The writings were rated in terms of organisation, vocabulary, language use and mechanics. Four categories of errors, including misspellings, borrowings, coinages, and calques were used to identify the errors in the learners’ use of nouns, verbs, adjectives, and adverbs. It revealed that the number of errors negatively correlated with composition quality. She found that a large majority of errors (74.8%) were misspellings, followed by borrowings (i.e., complete language shift from L2 to L1), coinages (adapt an L1 word to an L2 word with similar sound or form,) and calques (literal translation, table study [desk]). No significant correlation between the rate of lexical errors and the writing scores was found. Although misspellings outnumbered the other four lexical error types, they had no significant effects on learners’ writing quality. Borrowings and coinages were weakly negatively correlated with the quality of writing, while calques had a positive impact on the quality of the writing.

In a related larger study, Llach (2011) further examined lexical errors in compositions made by a group of 235 primary school Spanish learners over two years, in their fourth and sixth grades. The findings revealed that the sixth graders committed a lower ratio of lexical errors than the fourth graders after receiving more than 200 hours of English language instruction for two years in all seven categories. Misspellings were the most frequent in writing performance by both groups, followed by borrowings by the fourth graders and by calques by the sixth grade students. There was a positive correlation between the proportion of lexical errors in compositions and the score of the writings written by the two groups, which was particularly stronger for the fourth graders. However, the correlational relationships varied across the error types and two groups of learners. This suggests the influence of errors on writing quality might depend on different groups of learners, necessitating more research on erroneous use of vocabulary by learners of different backgrounds.

The review here has shown that lexical errors are among the most common types of writing errors, committed in a wide range of genres such as free writing, narrative, expository, compare-contrast, and argumentative essays which were mainly written by university students in a formal context. In these studies, lexical errors were explained by reference to L1 and L2 influence; yet, L1-based errors were more frequent in some studies (e.g., Li, 2015; Phuket & Othman, 2015) than others (e.g., Chan, 2010; Hemchua & Schmitt, 2006; Llach, 2007, 2011). The implication is that each group of learners of different L1 backgrounds and in varied educational contexts might commit errors in different ways, which warrants more research.

2.2.2.3 Related studies on lexical errors in IELTS writing

Research on lexical errors in IELTS writing has been rare. One exception is Picot’s (2017) study, which replicated Hemchua and Schmitt’s (2006) on Thai EFL learners and explicitly examined lexical errors in writings made by 20 Greek 18-26-year-old learners of IELTS in an IELTS learning centre. The learners were required to write an essay of 300-350 words on the topic of how many children a family should have. Picot (2017) reported similar results to Hemchua and Schmitt’s (2006) study. The six most common lexical errors, in order of frequency, were semantic word selection, preposition partners, calque, near synonyms, suffixes, and semantic ones, while Hemchua and Schmitt’s (2006) order was: near synonyms, preposition partners, suffixes, calques and verbs.

Other research targeted errors in general (Bagheri & Riasati, 2016; Divsar & Haydari, 2017; Muller, 2015; Pouladian, Bagheri & Sadighi, 2017). These studies generally found lexical errors alongside other writing errors in reference to the IELTS scoring rubrics, including task response, cohesion and coherence, lexical resource and grammar range and accuracy. For Iranian adult learners of IELTS examined in Bagheri and Riasati’s (2016) and Pouladian, Bagheri and Sadighi’s (2017) studies, erroneous use in lexica resource was the second most common, after grammatical inaccuracies. Misuse of collocations, idioms, spellings, and word choice were the most frequent lexical errors found in the IELTS Writing Task 2 scripts in Bagheri and Riasati’s (2016) study. Guided by James’ (1998) taxonomy, Pouladian, Bagheri and Sadighi (2017) revealed formal errors more than doubled semantic ones, of which distortions or misspellings accounted fo nearly 50% and calques were the second most common. With a corpus of 70 sample IELTS essays from band 5 to band 8, which were contributed to an accredited IELTS learning website by writers from all over the world, Divsar and Haydari (2017) reported word mischoice to be the most frequent, followed by erroneous use in verb form (including tenses and inflections), misspellings and noun misuse.

There is a dearth of prior research on the relationship between lexical errors and IELTS writing quality. Muller’s (2015) and Sanavi’s (2014) were useful studies that reported the relationship between general writing errors and the IELTS Writing Task 2 performance quality. For example, Muller (2015) compared writing error rates and types produced in IELTS Task 2 exemplar essays of bands 6.0, 6.5 and 7.0, published by IELTS and found more errors in lower band scores. Adopting a different approach to examining errors, Sanavi (2014) used a learner corpus of 60 Task 2 essays of one-band difference (5, 6, and 7) written by Iranian EFL learners to explore the relationship between grammatical, lexical, and mechanical errors and essay scores. It was found that lexical errors came as the second most common type of writing errors after grammatical ones for the essays of bands 5 and 7, but as the third for band 6. It was notable that essays of band 7 comprised more lexical errors than those of the other two although the difference was not statistically significant. For lexical errors, word mischoice and word misformation were the two most common errors, followed by collocation misuse and coinage.

The research reviewed here has tended to examine lexical errors together with other writing errors made in IELTS writings by adult learners in formal settings of universities (Bagheri & Riasati, 2016; Pouladian, Bagheri & Sadighi, 2017) or does not specify learners’ backgrounds (Divsar & Haydari, 2017; Muller, 2015; Sanavi, 2014). Further research is warranted to understand lexical errors in IELTS Writing Task 2 by learners in other settings. While research on quantitative measures of lexical richness is abundant, there is a scarcity of research that has explored all the four dimensions of lexical resource (lexical density, lexical sophistication, lexical variation and lexical accuracy). The present study therefore analysed learners’ lexical resource in operation in writing by examining all four aspects in two writing task versions/topics and related them to the scores of their IELTS writing performance.

3 RESEARCH METHODOLOGY

This section describes the tools for data collection, data collection procedure and data analysis. Two main sources of data were questionnaire data and IELTS Writing Task 2 performance data. Additional sources of data include the writing performance scores and learners’ ratings of the difficulty of their two IELTS Writing Task 2 essays.

3.1 Questionnaire

3.1.1 Questionnaire design

The questionnaire was employed as a research tool to explore Vietnamese learners perceptions of IELTS Writing Task 2. It was designed with four main parts: i) background information; ii) the learners’ motivation for learning IELTS; iii) their perceptions of the IELTS Writing Task 2 difficulty; and iv) their perceived lexical self-efficacy. The questionnaire items were designed and/or adapted from different sources. Table 7 summarises the design of the questionnaire (see Appendix A for the questionnaire).

Part 1 was about the learners’ background information which included 11 open-ended and closed-ended questions. Part 2 of the questionnaire explored Vietnamese IELTS learners’ reasons/motivations for learning IELTS with one item asking learners to identify reasons for studying IELTS and 10 closed-ended items based on a 7-level Likert scale about their further motivations related to the IELTS test. These items were designed based on Chapelle at al. (2019) and Yang and Badger (2014).

Part 3 of the questionnaire sought to understand the perceived difficulties that IELTS learners faced with IELTS Task 2 writing, drawing on the frameworks of ESL/EFL task difficulty (Robinson, 2011; Skehan, 2016). These researchers have identified factors tha impact learners’ task performance and these factors are task-/topic-specific, linguistic in nature, learner-inherent and subject to task conditions. For the focus of the present research, Part 3 deals with: i) task-related factors (12 items); ii) linguistic factors (12 items); and iii) personal factors (14 items). All the items were closed-ended.

In this study, items related to task conditions (e.g., task prompts, time for writing) were addressed as task-related factors.

With a particular interest in lexical resource, Part 4 of the questionnaire further explored learners’ perceived lexical self-efficacy. Self-efficacy was measured by operational ‘can do’ statements with vocabulary use. Design of perceptions of lexical self- efficacy, in the present research, was informed by Nation’s (2013) descriptions of what it means by knowing a word, by Read’s (2000) framework for lexical assessment, and by IELTS Writing Task 2 marking criteria. According to Nation (2013), knowing a word entails knowing its form, meaning and use in different receptive and productive dimensions. For this study, we focused on productive vocabulary use (see Table 1 in Section 2.1.3), how learners produced words and used them in IELTS Writing Task 2 performance. Learners were asked about what they were able to do with lexical words in written language production. IELTS marking criteria for Writing Task 2 scripts were an additional practical reference for our questionnaire design. Measures of lexical self-efficacy were measures of lexical resource delineated in the criteria: lexical accuracy (word choice, word form, word collocation), lexical diversity (lexical range), lexical sophistication (use of rare or uncommon words), and lexical fluency (flexible use of words to express meanings appropriately in contexts).

Table 7: Summary of questionnaire design

3.1.2 Questionnaire administration

3.1.2.1 Piloting

The designed questionnaire was first piloted with many IELTS learners who had studied the IELTS Writing Task 2 for at least two months in multiple rounds, and the information gleaned from earlier rounds informed revision and refinement of the questionnaire. Prior to the main data collection, the revised questionnaire had been piloted with 51 IELTS learners and the Cronbach’s Alpha reliability test shows satisfactory results, from .85-.91 (Table 8). The IELTS learners with whom the questionnaire had been piloted were not included in the official questionnaire data. They participated in the piloting on a voluntary basis.

Table 8: Reliability statistics of the piloted questionnaire $( N = 5 7 )$

3.1.2.2 Main data collection

A convenience method of sampling (Dörnyei, 2007) was initially employed. The researchers first reached out to IELTS teachers and then their IELTS classes who were within our physical access in a city in central Vietnam in order to inform them of the research project. The purposeful focus was on IELTS learners who had learnt IELTS Writing Task 2 for at least two months so that they could report their writing experience. We closely observed the integrity of ethics protocol to ensure that participation was entirely voluntary and the participants could withdraw from the research any time without consequences. The teachers and their IELTS learners were fully informed of the research and they gave their written consent prior to data collection (see Appendix B for information sheets and consent forms). The official pencil and paper questionnaire was administered to 212 IELTS learners in 17 IELTS classes taught by 13 IELTS teachers in a city in central Vietnam, of whom 86 had written two IELTS Writing Task 2 essays (see Section 3.2). The questionnaire was in Vietnamese to reduce possible misunderstandings due to language proficiency, and it took the learners about 15 minutes to complete. The questionnaire copies were returned in class after completion. Each learner participant received a small sum of cash for their contribution.

3.1.3 Questionnaire analysis

The questionnaire returns were first checked and irrelevant data was removed.

The data from those of the learners who had learnt IELTS Writing Task 2 for less than two months (see the focus of the study in Section 3.1.2.2) and those who left (large) parts of the questionnaire incomplete were excluded yielding a total of 200 for the current analysis. The questionnaire data were entered into an Excel spreadsheet. They were then double-checked carefully and imported into the Statistical Package for the Social Sciences (SPSS 20.0) to obtain frequency counts and descriptive statistics of the items that represented the different constructs of learners’ perceptions.

Regarding the great individual variation in data of Part 3 (Factors influencing IELTS Writing Task 2 performance) and Part 4 (Lexical self-efficacy in IELTS Task 2 writing ) of the questionnaire, the frequency counts and percentages were provided alongside mean and standard deviation values and as such, the seven categories of the scale were merged into three: 1-3 (disagreement), 4 (neutrality), and 5-7 (agreement) to better summarise the trends and fit in the table space limit. The Cronbach alpha values for the constructs of the questionnaire were from .77 to .90 (Table 9), indicating satisfactory reliability, according to Field (2005).

Table 9: Reliability statistics of the official questionnaire (N=200)

The participants’ background information is summarised in Table 10. The large majority of the learners were school students and university students, and only 26 of the participants (13%) were working. About two-thirds were female. On average, the learners had learnt IELTS Writing Task 2 for about 8-10 months at the time of data collection, though there was great individual variability.

Table 10: Participants’ background information (N= 200)

The data related to those who wrote the two essays and completed the questionnaire were further analysed for correlations: i) between their perceived personal factors and the writing quality; and ii) between their reported lexical self-efficacy and the writing quality. Writing quality was defined as the performance scores including the score given to the lexical resource criterion, and the overall band score by IELTS raters. Kendall’s tau_b (τb) correlation tests for the non-normally distributed data were run. Field (2005) argues that the Kendall’s tau_b (τb) correlation test was more accurate than its nonparametric counterpart (Spearman rho) especially when there were equal values in the data. The significance level was conventionally set at .05. Kolmogorov-Smirnov tests were run to test normality of data distribution (Field, 2005). Following Lu (2012), the correlation guide recommended by Wolfe-Quintero et al. (1998) was used to interpret the correlations results: correlation coefficients from .250 to <.450 were considered weak; coefficients of from .450 to <.650 medium, and coefficients of from .650 onwards strong.

3.2 IELTS Writing Task 2 scripts

3.2.1 Tasks and procedure

3.2.1.1 Task selection

The IELTS Writing Task 2 prompts were sourced from the Cambridge IELTS books to maintain high standards of tasks and task rubrics, since they had been validated, according to an IELTS IDP research coordinator. For the purpose of the current study, two writing tasks about the topics of living in a foreign country (Essay 1) and community service (Essay 2) were selected for the main data collection tool (see below for the tasks and also see Appendix C). Use of different task versions/topics was to further explore possible task/topic impacts on learners’ lexical resource, since research has shown that topics could be one potential factor (e.g., Kyle & Crossley, 2016; Ryoo, 2018). For such a purpose, the task rubrics were taken into consideration upon selection. Both tasks required learners to discuss controversial issues related to studying overseas and voluntary community service, and had the same form of question ‘To what extent do you agree or disagree?’ The tasks had been given to the above-mentioned IELTS expert for feedback before being piloted with eight volunteer Vietnamese IELTS learners. Learners were required to write about 250 words with a time limit of 50 minutes.

ESSAY 1

You should spend no more than 50 minutes on this task.

Write about the following topic:

Living in a country where you have to speak a foreign language can cause serious social problems, as well as practical problems.

To what extent do you agree or disagree with this statement?

Give reasons for your answer and include any relevant examples from your own knowledge or experience.

Write at least 250 words.

ESSAY 2

You should spend no more than 50 minutes on this task.

Write about the following topic:

Some people believe that unpaid community service should be a compulsory part of high school programs (for example working for a charity, improving the neighbourhood or teaching sports to younger children).

To what extent do you agree or disagree with this statement?

Give reasons for your answer and include any relevant examples from your own knowledge or experience.

Write at least 250 words.

3.2.1.2 Task piloting

Initially, two tasks, one about whether music could connect people of all ages and cultures, and the other about unpaid community service were sourced. The former was de-selected because this task, while involving a familiar topic (music), and no specialised knowledge, was constraining and challenging to write “well” to expand ideas and lexical range as reported in the first pilot round with six Vietnamese IELTS learners. The ‘living in a foreign country’ task was therefore a replacement. The two writing final tasks described above were then piloted with eight Vietnamese IELTS learners (who were not included in the main data collection and who participated voluntarily) in two rounds.

The aims were to test the task prompts, and to see whether students understood them and were able to produce such a number of words within the given amount of time. The learners interviewed right after they completed the tasks shared that the tasks were clear and their writing went “ok”. All the eight learners were able to write more than 250 words.

3.2.1.3 Procedure for data collection

IELTS classes in a city in central Vietnam were identified and information about the research was sent to the respective teachers in charge who helped inform learners of the research. Those learners who had been learning IELTS for at least two months and were willing to participate were invited to write two Writing Task 2 essays. With their consent, each learner hand-wrote each of the two Task 2 essays on ready-made paper sheets, which were one week apart because a longer time interval might have affected learners’ language development (Laufer & Nation, 1995). The learners wrote the two essays in counterbalanced design, so that there was an equal number of learners who wrote Essay 1/Essay 2 first. As specified in the IELTS Writing Task 2 prompts, learners wrote at least 250 words per task in their normal IELTS class hours as a progress test. They were allowed up to 50 minutes to write each essay. They were not allowed to use any resources during their writing. The specified minimum word length was appropriate for the present study, since text lengths of from 200 words are believed to provide consistent results in terms of lexical use (Laufer & Nation, 1995). Each learner participant was paid a small amount of money, as appreciation tokens for their contribution. After the learners had completed writing each essay, they filled out an exit questionnaire about the writing task they had completed, which aimed to understand their perceived task difficulty (see Appendix C).

3.2.2 Data set

3.2.2.1 IELTS Writing Task 2 scripts

A total of 215 IELTS Writing Task 2 scripts on two topics (Living in a foreign country and Community service) were hand-written by Vietnamese IELTS learners in 12 respective IELTS classes (taught by nine different teachers) in a city in central Vietnam. The scripts were de-identified, with codes given for analysis.

The scripts by learners who wrote only one of the essays and those who had studied IELTS writing Task 2 under two months were first eliminated and so were the scripts with unreadable handwriting. The remaining handwritten essays were de-identified, typed as they originally were, and saved as .doc files. Next, scripts below the minimum threshold of 200 words were removed, yielding a corpus of 172 scripts (86 per topic). Of these 86 learners who wrote the two essays, 45 of them were female, and 41 male. They were aged from 14 to 31 years (M = 20.02, SD = 3.72). Forty of them (46.5%) were university students majoring in different disciplines of which medicine was most popular, and 35 (40.7%) were lower and upper secondary school students; the remaining (12.8%) were learners who were mostly working (except one unemployed), namely teachers, doctors and tour guides. They had widely varied experiences with IELTS Writing Task 2, from two to 60 months, with an average length of IELTS Task 2 study of about 10 months (M = 10.34; SD = 11. 99). A majority of them (79/86 or 91.9%) had not taken an IELTS test before, and five had studied abroad from 5 days to 10 years.

Table 11 summarises the Writing Task 2 script data. The results of a Wilcoxon signed rank test show that the mean length (measured by number of tokens) of the Essay 1 scripts (M = 312.94, SD = 75.21) did not differ statistically from that of Essay 2 (M = 312.81, SD = 64.04), Z = -.381, p = .703, suggesting the learners wrote the two essays in similar lengths.

Table 11: IELTS Writing Task 2 scripts

3.2.2.2 Learners’ perceived IELTS task difficulty

Upon completing each essay, the learners were required to rate the essay difficulty through an exit questionnaire (see Appendix C) on a 7-point scale from 1 = very difficult, 2 = difficult, 3 = quite difficult, 4 = quite easy; 5 to 6 = easy, 7 = very easy). Students were asked to provide reasons for their rated difficulty.

3.2.2.3 IELTS Writing Task 2 scores

The handwritten scripts were scanned and coded for grading by the IELTS examiners arranged by IELTS IDP; scores were provided in four criteria: i) Task response, ii) Coherence/Cohesion, iii) Lexical resource and iv) Grammatical range and accuracy, as described in the IELTS Writing Task 2 scoring rubric with additional, brief comments on lexical resource.

3.2.3 Data analysis

3.2.3.1 Analysis of quantitative lexical measures

The texts with a minimum word length of 200 words were then ‘cleaned’ by fixing obvious spelling mistakes as adopted in Lu (2012); the misspelt words were tagged using angle brackets < > and word/grammatical forms that did not exist in English were also fixed and tagged (e.g., become ). These tags were later removed before analysis. Incorrect use of vocabulary was not fixed nor tagged. Henricksen (1999) contends that attempts to use lexical items, though incorrect, demonstrate ‘partial knowledge’ of L2 vocabulary. Other studies (e.g., Crossley et al., 2011; Kojima & Yamashita, 2014) also do not exclude errors in lexical use from analysis. Each of the scripts was saved separately and then turned into plain text files for analysis.

Following Lu (2012), Lexical Complexity Analyzer (LCA), a computational system was used to analyse all the measures of lexical density, lexical variation and sophistication as discussed in the literature review. The rationale for using a large set of lexical measures was two-fold: i) to add to a lack of research that uses a large set of measures to gauge lexical sophistication and lexical variation in written language production that are derived from the same computational program; and ii) to explore how they are affected by writing tasks/topics and how they are related with each other and with the overall writing/lexical performance (further see Section 2.2.1.4).

There were, in total, 26 measures of lexical resource: lexical density (1 measure), lexical sophistication (5 measures) and lexical variation (20 measures). Table 12 summarises these measures. The cleaned text files were inputted into the LCA system to automatically obtain all the values except D value. The computation of D value followed Lu (2012). First, the cleaned text files were turned into the CHAT3 (Codes for the Human Analyses of Transcripts) format by the function of the Computerised Language Analysis (CLAN) “textin utility” (p. 198). Then they were “subjected to three times of vocd analyses. The average of the three analyses served as the D value of the sample” (Lu, 2012, p. 196).

Table 12: Summary of quantitative measures of lexical density, lexical sophistication and lexical variation

The process of deriving the other 25 lexical measures in the present study is delineated as follows (see Lu, 2012 for further details).

1. Each of the cleaned text files was tagged for the part of speech (POS) of each token by means of the Stanford tagger (Toutanova, Klein, Manning, & Singer, 2003).
2. The POS-tagged texts were then lemmatised through the morphologica analyser, MORPHA (Minnen, Carroll, & Pearce, 2001) to obtain information on lemmas and inflectional forms of a word. Following Lu (2012), these different inflectional forms of the same lemma were considered as one type in the present study and “a word, lexical word, or a verb was sophisticated if it was not among the 2000 most frequent words in the BNC word list” (p. 197).
3. Next, the lemmatised text files were run by a python script to calculate the lexical measures. The number of word types and word tokens was also computed in the process (further see Lu 2012, p. 197).

The lexical measures derived from the LCA were outputted in the form of an Excel spreadsheet for subsequent analyses by means of SPSS (version 20.0).

3.2.3.2 Analysis of lexical errors

Lexical accuracy is another sub-criterion for marking IELTS Writing Task 2, alongside vocabulary range and use of uncommon words. It also reflects the quality of lexical use in writing (Read, 2000). Lexical errors, in the present study, were defined as any erroneous non-target like use of lexical words in the IELTS Writing Task 2 scripts written by the Vietnamese IELTS learners. Lexical words were defined according to Lu (2012) as encompassing open-ended words such as nouns, verbs, adjectives, and adverbs derived from an adjective by adding -ly suffix, or adverbs that function both as an adjective and an adverb. Therefore, errors related to closed-ended functional or grammatical words were not included. In particular, misuse of tenses, articles, determiners, prepositions of time and place, pronouns, quantifiers, conjunctions, word order (except order of lexical words) and punctuation were not explored in the present analysis.

However, since errors related to the use of open-ended lexical words might involve the misuse of their grammatical patterns, these errors were built in the respective lexica words. For example, omission of the inflectional morpheme -s that marks plural nouns or third-person singular present tense (3SG-s), or omission of copula be that is supposed to go with an adjective, a noun or noun phrase, were counted as lexical errors in this sense.

For the purpose of the current study, the frameworks of error analysis in previous research (e.g., Hemchua & Schmitt 2006; James 1998; Llach, 2011) were referred to identify lexical errors. However, since a pre-determined list of error types might hinder discovering other errors, a data-driven approach was employed to explore errors as they emerged from the data. Therefore, identifying lexical errors in the corpus of the Writing Task 2 scripts was an iterative process, which involved reading and re-reading the scripts multiple times to understand and identify lexical errors made by the Vietnamese IELTS learners. New categories of errors were added as they unfolded.

Lexical use in Writing Task 2 scripts was explored and searched for errors initially by Trang. By that means, and further informed by the above-mentioned frameworks, a tentative taxonomy of errors was built. The taxonomy was revised, updated and refined as Binh and Nhu further explored the Writing Task 2 script data for lexical errors. Each type of errors was operationalised in a clear manner with the ultimate aim of maximising transparency and reliability. The error taxonomy with the operational definitions of error types and subtypes is described in Appendix D. Lexical errors were related to spelling, word formation, word choice, and collocational use among others.

Coding was manual and tagged using colour codes directly on the original hand-written scripts (uncleaned versions), except coding of misspellings. Misspelled words were identified using the Spell Check function in Word and also annotated using colours. The highlighted misspellings were then noted manually and the counts of misspelt words for each essay were entered into an Excel spreadsheet for later analyses. Both correct American and British spelling was accepted.

In the case of the repeated error of the same lexical word, it was counted as one error. However, when the same type of error of different lexical words was committed, different errors were counted. Different types of errors (i.e. spelling, word choice, word form, etc.) of the same lexical word were coded as different errors. Following Muller (2015), “if an error was detected that, upon correction, required changes in other parts of the text, only the initial error was counted” (p. 8). For instance, in the sentence, “Student [Students] learn a lot from participating in community service.” (E2-T5-05), only one error related to pluralisation ‘Student’ was counted. In the current analysis, only errors tha involved explicitly deviated forms from the target language use, and substantiated by sufficient contextual clues were counted. Errors that were confusing to decide were not taken. The Oxford’s Collocation Dictionary, Macmillan English Dictionary for Advanced Learners, Corpus of Contemporary American English (COCA), and British National Corpus (BNC) were employed as necessary as a reference to judge the learners’ lexical accuracy.

Two subsamples of the scripts (36 essays or 21%) were coded independently by Nhu or Binh separately and another EFL lecturer who completed a Master course in Applied Linguistics in Australia.

Table 13: Inter-reliability results for coding lexical errors

Table 13 indicates the inter-reliability results in both percentage agreement (from 80.6% to 100%) and Kappa (k) (from .65 to 1.0), which were satisfactory (Yin, 2015). Where there were differences or disagreements, they were further discussed and resolved between the coders. Nhu and Binh then coded the remaining data for errors using the derived taxonomy. A paid student entered the identified errors accordingly into a ready-made Excel spreadsheet with labelled categories of errors. The Excel data were checked and double-checked for accuracy before being imported into SPSS (20.0) for further analysis.

3.2.3.3 Statistical analysis

SPSS (Version 20.0) was used as a tool to obtain descriptive statistics and run statistical tests where relevant. A series of non-parametric Wilcoxon-signed rank tests were conducted to examine the effects of task version (topic) on the different measures of lexical resource. For multiple comparisons, Bonferroni correction was adopted to avoid Type 1 errors. To explore the links between lexical measures (lexical density, lexical sophistication, lexical variation and lexical accuracy) and the quality of writing performance (lexical score and overall band score), a series of Kendall’s tau_b (τb) correlation tests were conducted for the non-normally distributed data, as described earlier. Additional correlation tests were run among measures of lexical sophistication/ variation. Since the present study employed multiple measures of lexical richness, we were also interested in finding which measure(s) of the same construct correlated most strongly with the writing performance, and which measures among the similar ones were not strongly linked to each other. The interpretation of the correlations results drew on Wolfe-Quintero et al. (1998) (see Section 3.1.3).

3.2.3.4 Analysis of learners’ reasons for task difficulty

As described in the data set, in addition to rating essay difficulty on a seven-level Likert scale, the learners were also asked in an open-ended question to provide reasons for their perceived difficulty upon completing each essay. Analysis of their written responses was conducted in the original Vietnamese language as recommended by Casanave (2010). It was an iterative process of reading and re-reading to look for the themes that surfaced in the data. The themes were devised, and subject to confirmation, reconfirmation or disconfirmation (Newman, 2014). Following Yin (2015), quotes for illustration were presented in Vietnamese and English (translated versions) for the reader to make sense of the data. The coding of themes and translations was double-checked by a Master student in Applied Linguistics. Agreement reached 90% and any differences were discussed between Trang and the student to resolve.

3.3 Validity and reliability

Validity and reliability were maximised through our efforts in every step of the research design, data collection and data analysis. Validity refers to “the extent to which we can trust the research findings” (Paltridge & Phakiti, 2018, p. 31). The trustworthiness of the results of the present study was ensured by a number of measures:

1. aligning the research aims, research questions and the research methods
2. adopting purposive sampling (e.g., IELTS learners who had a minimum of two months learning writing IELTS Task 2)
3. operationalising the (sub)constructs in a clear manner and based on established frameworks
4. piloting the relevant research tools carefully prior to official data collection
5. Vietnamese L1 (with examples given) was used in the questionnaire and Exit questionnaire after task completion to maximise understanding; accuracy of translation was taken into account through third-party double-checking and back translation
6. trust was built with the learner participants by observing confidentiality and anonymity/de-identification for them to share their perceptions and write IELTS Writing Task 2 Essays with comfort
7. multiple sources of data were used (e.g., perception questionnaires, IELTS Writing Task 2 scripts about two topics, overall writing scores and sub-scores, learners’ ratings of task difficulty and reasons)
8. using multiple measures of lexical resource/richness
9. conducting quantitative analysis of the data via SPSS and automatic analysis of quantitative lexical measures using LCA
10. adopting “validity as quality of the craftsmanship” (Kvale & Brinkmann, 2009, p. 248) with regards to analysing the qualitative data (lexical errors and learners’ stated reasons for their ratings of task difficulty).

Reliability is concerned with how replicable the results are (Cohen, Manion & Morrison, 2018) and it was maximised by:

1. explicitly describing the participants and the constructs
2. making explicit and transparent every step of collecting, coding and analysing data
3. conducting Cronbach’s Alpha reliability analysis to ensure the internal consistency of the measures
4. conducting formal inter-coder reliability analyses for different categories of dependent variables where relevant by means of both the percentage agreement and the kappa coefficient between the two coders/markers.

4 FINDINGS

This section presents the findings of the current research project, which are organised in two main parts. Part 1 reports the findings of the questionnaire data about learners’ perceptions of IELTS Writing Task 2. Part 2 presents the results related to performancebased lexical resource in IELTS Writing Task 2 scripts by Vietnamese IELTS learners.

4.1 Part 1: Questionnaire findings

The questionnaire explored the perceptions of 200 Vietnamese IELTS learners about IELTS Writing Task 2 and their lexical self-efficacy. The results, related to each of the four main research questions, are presented below.

4.1.1 RQ1: What motivates Vietnamese IELTS learners to learn IELTS?

Table 14 presents the reasons for which the Vietnamese IELTS learners in the present research reported studying IELTS. The frequency column denotes the number of learners who chose the corresponding response and the equivalent percentage was calculated as the proportion of the number of mentions/responses out of 200 participants. Note that each learner could choose more than one response. There was a variety of educational, work-related and personal reasons, of which the most popular was to enhance general language proficiency (79%) and get their ideal jobs (59.5%). About half of the learners reported studying IELTS mainly to obtain an internationallyrecognised qualification and apply for foreign scholarships and to meet the national English requirements at different undergraduate programs. Learning IELTS for persona satisfaction was reported by 37% of the learners. Nearly one-third of them attended IELTS courses to pursue postgraduate studies. Learning IELTS to please parents was also mentioned by 11.5% of the participants. The other reasons added (4%) were related to migration, teaching, and reading English medium materials.

The learners further reported motivations related to the IELTS test by identifying the extent to which each statement was true of them on a seven-level Likert scale (1: Very untrue of me, 2: Untrue of me, 3: Somewhat untrue of me, 4: Undecided, 5: Somewhat true of me, 6: True of me, 7: Very true of me). Table 15 also further shows that they were motivated to learn IELTS for its accessibility (in terms of materials, test sites, available marking criteria) (items 1-5), and its credibility as an internationally recognised and reliable test (items 6-10). In the learners’ perceptions, the latter (M = 6.14, SD = .69) appeared to be a greater incentive than the former (M = 4.84, SD =1.10).

Table 14: Learners’ reported reasons to study IELTS

Table 15: Descriptive statistics for learners’ reported motivations to learn IELTS (N=200)

4.1.2 RQ2: What factors do Vietnamese IELTS learners identify as influencing their IELTS Writing Task 2 performance?

4.1.2.1 Task-related factors

In the questionnaire, the Vietnamese IELTS learners were also asked to identify the extent of influence of task-inherent factors in writing IELTS Writing Task 2 on a sevenlevel Likert scale (1: not at all, 2: not really, 3: very little; 4: undecided, 5: to a certain extent, 6: to a large extent, 7: to a very large extent).

The results (Table 16) show that topic unfamiliarity (M=5.50, SD=1.31) was perceived as a clear factor seemingly influencing task performance more than topic disinterest (M=4.63, SD=1.51). The novelty of the discursive genre was generally perceived as an obstacle (M= 4.98, SD=1.52). However, when it comes to specific IELTS Writing Task 2 types (items 9-12), the responses were quite varied (M= 3.76-3.90 with large SD values), with from 43.5%- 46.5% of the learners reporting Writing Task 2 types having no or little influence and 35- 43% identified them as a factor. IELTS Writing Task 2 as a timed performance (items 4, 5) and unavailability of external resources were additionally identified as influencers.

IELTS Writing Task 2 as an open-ended task and no guidance were reportedly not challenging for all the learners, with about half and 43% of the learners identifying them as a hindrance respectively.

Table 16: Learners’ perceptions of task-related factors (N=200)

4.1.2.2 Linguistic factors

Regarding linguistic factors, the learners were to identify the extent to which each statement was true of them on a seven-level Likert scale (1: Very untrue of me, 2: Untrue of me, 3: Somewhat untrue of me, 4: Undecided, 5: Somewhat true of me, 6: True of me, 7: Very true of me). Table 17 shows the descriptive statistics for the linguistic difficulties that Vietnamese IELTS learners reported having when writing IELTS Task 2. Vocabulary was perceived as one of the most challenging aspects. In particular, writing with appropriate word choice and varied vocabulary was difficult for a large majority (from about 90%) of the learners (mean values of nearly 6). Using lexical devices such as on-topic vocabulary and alternative words and opposites to establish connection was also challenging, M = 5.05 (SD = 1.41) and M = 4.77 (SD=1.48) respectively. On the other hand, use of grammatical cohesive means such as referents (M = 3.70; SD = 1.50) and linking words (M= 3.99, SD = 1.55) was less difficult in learners’ perceptions, though opinions were quite divided among learners.

Idea development and organisation (items 6-8) received mixed responses. In particular, writing topic sentences, developing topic/main idea and paragraphing were each reported as difficult for about slightly more than 50% of learners, while they were not so for about one-third of the learners. Writing grammatically-correct sentences was reported as challenging alongside use of different sentence structures and word/ phrase/sentence combination by the majority of the learners.

Table 17: Learners’ perceptions of linguistic difficulties (N=200)

4.1.2.3 Personal factors

On the same seven-level Likert scale as in linguistic factors, the learners also identified different sources of anxiety when they wrote IELTS Task 2 (Table 18). Self-oriented anxiety received more unanimous agreement with an average mean score of 5.53 $( \mathsf { S D } = . 9 7 )$ than examiner-oriented anxiety $( \mathsf { M } = 4 . 7 6 , \mathsf { S D } = 1 . 0 7 )$ . Self-inflicted fear sourced from the learners’ own concerns about timely task completion $( \mathsf { M } = 5 . 2 1$ , $\mathtt { S D } = 1 . 6 4 )$ , task response $( \mathsf { M } = 5 . 5 3 , \mathsf { S D } = 1 . 3 2 )$ ), and lack of practice $( \mathsf { M } = 5 . 4 9 ,$ , $\mathtt { S D } = 1 . 3 4 )$ . Other sources of self-imposed anxiety, namely achieving desired band scores and conveyance of intended meanings were identified as most worrying by 88% of the learners (M = 5.79, SD = 1.27 and M = 5.65, SD = 1.20 respectively).

Examiner-oriented fear was geared towards examiners’ unfavourable evaluation of their essays in view of linguistic inaccuracy $( \mathsf { M } = 5 . 3 1 , \mathsf { S D } = 1 . 3 1 )$ and poor writing $( \mathsf { M } = 5 . 0 2 , \mathsf { S D } = 1 . 3 9 )$ ; these were the identified fears by the majority of learners: 80.5% and 72% respectively. However, fear related to inappropriate academic writing style, comprehensibility of their essay and such an affective factor as examiners’ liking invited mixed perceptions, being the fear by 57%, 54% and 46.5 % of respondents respectively.

With regards to L1 writing habits, the learners also reported that they tended to think in Vietnamese first and then translate their ideas into English $( \mathsf { M } = 4 . 9 1 , \mathsf { S D } = 1 . 7 5 )$ . Being indirect in their writing $( \mathsf { M } = 4 . 3 5 , \mathsf { S D } = 1 . 7 8 )$ , and avoiding being critical $( \mathsf { M } = 4 . 0 1 , \mathsf { S D } = 1 . 6 3 )$ received mixed responses (Table 18) with the former being identified as the practice of about 54% of the learners, but not so by 37%. Similarly, the latter was both true and untrue for about 40% of the learners. Notably, the learners reported not using the same word order as in Vietnamese $( \mathsf { M } = 3 . 0 6 , \mathsf { S D } = 1 . 8 5 )$ .

Table 18: Reported personal factors

4.1.3 RQ3: How do Vietnamese IELTS learners perceive their lexical self-efficacy in writing IELTS Task 2?

The questionnaire also probed into students’ perceptions of their lexical self-efficacy in writing IELTS Writing Task 2. They were asked to identify the extent to which each statement was true on a seven-level Likert scale (1: Very untrue of me, 2: Untrue of me, 3: Somewhat untrue of me, 4: Undecided, 5: Somewhat true of me, 6: True of me, 7: Very true of me). The results are summarised in Tables 19-21. In terms of lexical accuracy, the Vietnamese IELTS learners reported low self-efficacy to write with no misspelt words (M = 3.10, SD = 1.57) (note that misspellings were the most frequent errors in their IELTS Writing Task 2 performance, see Section 4.2.5). There was a higher level of self-reported confidence in using inflectional forms of words (M = 4.32, SD= 1.52), though responses were mixed with slightly more than half of the learners being confident, while of the remaining, 35.5 % not being so. However, learners perceived that they were more capable of using parts of speech of words (M = 4.76, SD = 1.41) and grammatical and collocational patterns correctly, M = 4.65 (SD = 1.26) and M= 4.85 (SD = 1.33), respectively.

Regarding lexical diversity, while learners reported being rather confident about their use of different parts of speech of words $( \mathsf { M } = 4 . 8 3 , \mathsf { S D } = 1 . 2 8 )$ , perceptions of their ability to vary their lexical use through on-topic words, synonyms/antonyms and specific words for a general concept were mixed with different levels of self-efficacy (Table 19). In other words, the issue of lexical variation appeared to pose different levels of difficulty for these IELTS learners.

Table 19: Learners’ perceptions of lexical accuracy (N=200)

Table 20: Learners’ perceptions of lexical diversity and sophistication (N=200)

For lexical sophistication, 45% of the IELTS learners reported a low self-efficacy in using low frequency words while just about one-third were confident and 22% were not sure. The different lexical aspects of fluent use received different responses. The results (Table 21) show that quite a majority of the learners reported being confident about their use of homonyms (71%) and homophones (64.5%) and formal/informal words (60%). There was greater individual variation in the remaining lexical aspects. Slightly more than half of the learners reported confidence in using multi-meaning words, and under half (47%) considered they could use appropriate words with literal/figurative meanings. These latter aspects of lexical fluency seemed to be challenging to differing degrees to the learners.

Table 21: Learners’ perceptions of lexical fluency (N=200)

4.1.4 RQ4: How do Vietnamese IELTS learners’ perceptions of their writing anxiety correlate with the quality of their IELTS Writing Task 2 performance?

The data of the learners who wrote the two essays and completed the questionnaire were further analysed for any correlations between the reported anxiety and writing performance (IELTS Writing Task 2 score). The results of the Kendall’s tau_b correlation tests (Table 22) demonstrate no significant correlations between the overall perceived level of anxiety, and both self-oriented and examiner-oriented anxiety and the writing performance (further see the IELTS Writing Task 2 scores in Section 4.2.2). All the correlation coefficients were below .250, with p values >.05.

Table 22: Correlations between perceived anxiety and writing performance

4.1.5 RQ5: How do Vietnamese IELTS learners’ perceptions of their lexical self-efficacy correlate with the quality of their IELTS Writing Task 2 performance?

Due to the non-normality of the data, Kendall’s tau_b correlation tests were run to explore the relationship between learners’ perceived lexical self-efficacy and the lexical score and overall score in each essay. The results (Table 23) show that the mean score of self-reported lexical efficacy had a significant positive correlation with both the overall score and the lexical resource score (τb = .273 and τb = .268 respectively in Essay 1, and τb = .180 and τb = .268 in Essay 2). Table 23 further shows the correlations between the sub-dimensions of lexical self-efficacy and the writing scores. All the correlations except self-efficacy in lexical variation were significant, but weak (co-efficients ranging from .192 to .287). Lexical diversity self-efficacy very weakly correlated with only the lexical performance in Essay 1.

Table 23: Correlations between learners’ self-reported lexical effcacy and IELTS writing performance

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

4.2 Part 2: Performance-based lexical resource

This section reports the measures of lexical resource in learners’ IELTS written scripts. The findings are presented in relation to each research question.

4.2.1. RQ1: To what extent do Writing Task 2 versions have an effect on each of the lexical measures (lexical density, lexical variation, lexical sophistication) of the IELTS Writing Task 2 performance by Vietnamese IELTS learners?

The measure of lexical density shows that the Essay 2 scripts displayed a higher level of lexical density than Essay 1, M = .52 (SD = .03) and M= .48 (SD = .04) respectively. The results of a paired-sample t-test show the difference was significant, $t(85)=-10.164$, $p<.001$, suggesting their vocabulary was denser in Essay 2. In other words, learners had more ideas/content to write about in Essay 2.

Lexical sophistication was measured in five indices as displayed in Table 24. The results show that the two essays differed in lexical sophistication only when it was measured by LS1 (the ratio of sophisticated words over the total number of lexical words), Z = .-2.624, p < .01. For the other measures of lexical sophistication, there were no significant differences between the two essays (all with p > .01).

Another dimension of vocabulary use is lexical variation which was measured by different indices. Lexical variation measures related to the number of different words (NDW) are summarised in Table 25. The Wilcoxon signed-rank tests show a significant difference between the two essays only for NDW-ER50 (mean of number of different words for ten random 50-word samples) and NDW-ES50 (mean of number of different words in ten 50-word sequences). That is, learners used more different words in Essay 2 than Essay 1 as measured by the former (Z = -2.507, p = .012) and the latter (Z = -3.939, p < .001).

Table 24: Lexical sophistication

Note. The Bonferroni correction for multiple tests was applied, so the alpha value for the Wilcoxon tests was adjusted to .05/5 = .01.

Table 25: Lexical variation based on NDW

*The Bonferroni correction for multiple tests was applied, so the alpha value for the Wilcoxon tests was adjusted to .05/4= .0125

The measures of TTR-based lexical variation are presented in Table 26. The results of a number of respective Wilcoxon signed-rank tests and paired-sample t-test as appropriate show no statistically significant differences in lexical variation between the two essays in all the measures except MSTTR and D value. In particular, the level of lexical variation measured by MSTTR was higher in Essay $2 \left( \mathsf { M } = . 8 1 , \mathsf { S D } = . 0 4 \right)$ than in Essay 1 (M = .79, SD = .04), Z = -3.868, $p<.007$. Similarly, measured by D value, lexical diversity was greater in Essay 2 (M= 104.06, SD= 23.55) than Essay 1 $( \mathsf { M } = 9 3 . 6 7$ SD = 23.55), $t(85)=-4.175$, $p<.001$.

Table 26: Lexical variation based on TTR

Note. *The Bonferroni correction for multiple tests was applied, so the alpha value for the Wilcoxon tests was adjusted to .05/7= 0.007143 **paired sample t-test for the normally distributed data of D value

Table 27: Lexical variation based on TTR of lexical word parts of speech

Note. *The Bonferroni correction for multiple tests was applied, so the alpha value for the Wilcoxon tests was adjusted to .05/9= .005556

Lexical variation was also examined by means of TTR of lexical word parts of speech (Table 27). The findings indicate an impact of writing task on use of lexical words in favour of Essay 1. In particular, Essay 1 elicited a higher proportion of verb types out of the total number of lexical words (VV2), noun variation (NV), adverb variation (advV) and modifier variation (modV) (all with p < .001). LV, the ratio of lexical word types out of the total lexical tokens was significantly higher in Essay 1 $( \mathsf { M } = . 6 5 , \mathsf { S D } = . 0 9 )$ than in Essay 2 $( \mathsf { M } = . 6 3 , \mathsf { S D } = . 0 8 ) , Z = - 2 . 9 1 8 , \mathsf { p } = . 0 0 4$ .

In summary, IELTS writing tasks influenced the variation of vocabulary use and task influence was subject to the particular indices employed to measure lexical variation, which needs careful interpretation (see Section 5.2.1).

4.2.2 RQ2: To what extent do Writing Task 2 versions have an effect on the quality of the IELTS Writing Task 2 performance? What were learners’ perceptions of the difficulty of the writing tasks?

The learners’ IELTS Writing Task 2 performance scores are presented in Table 28. Since the data were not normally distributed, the non-parametric Wilcoxon signed-rank test was conducted to compare the means in each category. The results show that these IELTS learners obtained similar overall band scores, and sub-scores in both essays (p > .01), though they tended to address the requirements of the task more satisfactorily in Essay 2.

Table 28: Writing Task 2 performance

Note. *The Bonferroni correction for multiple tests was applied, so the alpha value for the Wilcoxon tests was adjusted to .05/5= .01

Upon completing each essay, the learners were required to rate the essay difficulty on a 7-point scale (1 = very difficult, 2 = difficult, 3 = quite difficult, 4 = no idea; 5 = quite easy; 6 = easy, 7 = very easy) and provide reasons. The results show that the learners perceived both essays were quite difficult, but Essay 1 (M = 3.05, SD = .97) was reportedly more difficult than Essay $2 ( \mathsf { M } = 3 . 4 0 , \mathsf { S D } = 1 . 0 7 ) , Z = - 3 . 1 1 9 , \mathsf { p } = . 0 0 2$ , though their band scores were similar in both tasks, as shown in Table 28. Learners were also asked to explain their rated difficulty of each essay. This was an open-ended question, and it is interesting that topic was mentioned first and foremost by a majority of the learners as the top key reason. Most learners reported that Essay 2, writing about community work was easier, as the topic was more familiar to them. Topic familiarity was delineated in terms of it being more closely relevant to their daily life, and to their own experience, and its being a common ‘daily’, ‘practical’ topic:

“Chủ đề gần gũi với học sinh, dễ viết.” (E2-T7-07)

(Topic is close to students’ life, easy to write.)

“Chủ đề thực tế, có thể liên hệ dễ viết.” (E2-T7-04)

(The topic is real, practical. I can relate and write more easily.)

“Đề bài lần này là một chủ đề thông dụng hơn, có thể phát triển được ý dễ dàng.” (E2-T7-02) (This time, the topic is more popular, easier to develop ideas.)

“Là chủ đề hằng ngày, em đủ ý để viết.” (E2-T2-08) (It is a daily topic; I have enough ideas to write.)

“Chủ đề quen thuộc, gặp nhiều lần.” (E2-T2-11) (Familiar topic, I have encountered this topic many times.)

“Chủ đề dễ bắt gặp trong xã hội; nên ý tưởng để viết khá phong phú.” (E2-T1-12) (It is a common issue in society; I can write with rich ideas.)

“Chủ đề đang được bàn luận nhiều trong bối cảnh hiện tại.” (E2-T8-01) (This topic has been debated quite a lot in the current situation.”

Clearly, in the learners’ perceptions, Essay 2 topic familiarity facilitated idea generation in the process of writing. In contrast, the learners reported they did not have prior knowledge or experience with Essay 1 topic. Many learners commented:

“Chưa từng trải nghiệm, khó phát triển ý.” (E1-T7-03) (I haven’t experienced it [living overseas], it was hard to develop my argumentation.)

“Cần có trải nghiệm thực tế để hiểu rõ.” (E1-T5-04) (Need to have real life experience to understand well.)

“Tôi chưa từng nghe về chủ đề này.” (E1-T4-04) (I haven’t heard about this topic in anyway yet.)

“Không phải lĩnh vực tôi quan tâm; không có kinh nghiệm, thiếu kiến thức, nên thiếu ý tưởng.” (E1- T9-13) (It is not the area I have knowledge of; no experience, little knowledge, so few ideas to write.)

“Thiếu kiến thức xã hội để bàn luận.” (E1-T8-12) (Lack of social knowledge to discuss.)

“Chủ đề khá lạ lẫm, thiếu ý tưởng.” (E1-T5-21) (The topic is quite new, lacking ideas.)

Topic novelty as the learners viewed it was related to whether they had experienced it, or had knowledge about it or whether they were interested in it in order to have ideas to write. The next theme that emerged second to topic was vocabulary. Lexis and ideas were two accompanying core themes that learners mentioned about how the task/topic was difficult or easy for them. The learners recounted they lacked vocabulary to encode the intended meanings in Essay 1:

“Em không có kiến thức xã hội về chủ đề này, nên tìm từ vựng liên quan chủ đề khó.” (E1-T2-01) (I did not have social knowledge about this topic, so good vocabulary was challenging.)

“Rất khó, không đủ từ vựng” (E1-T9-11) (Very difficult indeed, not enough vocabulary)

“Không đủ từ vựng cho chủ đề.” (E1-T7-03) (My vocabulary for the topic is not enough.)

“Khó viết; chủ đề chưa biết, từ vựng ít.” (E1-T4-01) (Difficult to write, not known topic, limited vocabulary.”

In contrast, Essay 2, which was about a more familiar topic, as the learners commented, enabled them to have ready relevant vocabulary to use. One learner shared: “Topic is familiar, it was not hard to find relevant words”. Where the learners rated the topic difficult, they repeatedly cited how that topic could restrict access to ideas, and lexical items to encode such ideas.

While most learners perceived Essay 2 was easier, a minority of them perceived Essay 2 was more difficult, since they did not have experience of it and/or sufficient topic-related vocabulary to express intended meanings. Here we can see individual learners’ experience with a given topic might be very different, which could be both a disadvantage or benefit for learners, while writing IELTS Writing Task 2.

While topic and vocabulary were the two most overwhelming concerns for these Vietnamese IELTS learners, several students further mentioned they did not quite understand the task question in Essay 1, and feared that they would not respond properly to the requirements of the task. They also recounted lack of practice and training in IELTS writing and inadequate time to develop ideas clearly as additiona causes of their task difficulty.

In summary, the findings show that IELTS Writing Task 2 versions influenced how the Vietnamese IELTS learners used lexical words in their writing. Generally writing about community work (Essay 2) elicited denser, more sophisticated and more varied vocabulary than writing about living overseas (Essay 1). However, task influence depended on the particular indices used to measure lexical sophistication /variation. The learners’ perspectives show that the novel/unfamiliar topic was a very serious obstacle.

4.2.3 RQ3: How do lexical density, lexical sophistication and lexical variation correlate with the quality of the IELTS Writing Task 2 performance?

A number of Kendall’s tau_b correlation tests (for the non-normally distributed data) were run to explore the links between the lexical measures and the quality of the IELTS writing performance gauged by the overall band score and the lexical score of each essay. The results (Table 29) show lexical density did not correlate with either the overall band score or the lexical score in Essay 2, but it did, though negatively, in Essay1 with the lexical score (τb = -.193) and the overall score (τb = -.251). Yet, these correlations were very weak, implying that the mere presence of content words in learners’ writing was not always equated with a high score.

Table 29: Correlations between lexical density and IELTS Writing Task 2 performance

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

Table 30 summarises the correlation results related to lexical sophistication. Lexical sophistication when measured by VS2 and CVS1 positively correlated with both the overall band score and the lexical score in both essays and these correlations were all weak (τb = from .170 to .291 for VS2 and τb = from .170 to .292 for CVS1). LS1, LS2 and VS1, as indices of lexical sophistication, were not significantly associated with the quality of the writing performance in Essay 2, but they were in Essay 1 with the lexical score only with the exception of LS2 with both (τb = from .212 to .254). All the significant correlations were weak. Further results (Table 31 and Table 32) identified the lowest correlations were between VS2 and LS1 and between CVS1 and LS1, with τb = .410 for both in Essay1, and τb = .473 and τb = .474 respectively in Essay 2. Though the correlations were from weak to medium, they suggest: i) that among the many factors affecting the IELTS Writing Task 2 score, the use of sophisticated words might have some potential impact; and ii) that VS2 (the squared version of VS1) and CVS1 (corrected VS1) could be the most useful of all lexical sophistication measures, at least for IELTS Writing Task 2 performance by the Vietnamese IELTS learners in this study.

Table 30: Correlations between lexical sophistication and IELTS Writing Task 2 performance

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

Table 31: Correlations among lexical sophistication measures in Essay 1

**. Correlation is significant at the 0.01 level (2-tailed).

Table 32: Correlations among lexical sophistication measures in Essay 2

**. Correlation is significant at the 0.01 level (2-tailed).

With regards to lexical variation, the correlations between measures of lexical variation of the general word group and the writing quality are presented in Table 33. As can be seen in Table 33, the number of different words used in the essays as measured by NDW had a positive correlation with both the lexical (resource) score and the overall band score in both essays (τb = from .302 to .378). Other NDW-related measures did not show a significant association with the writing performance in Essay 2, except NDW-ES50 with the lexical score (τb = -.180). In Essay 1, NDW-50 was positively linked with the lexical score (τb = .179), while NDW-ER50 correlated with the overall band score (τb = .170). The correlation sizes were all very small, but the highest of all significant correlations in this group were between NDW and the overall writing performance (τb =.378 in Essay 1 and τb = .302 in Essay 2). Further correlation tests were run among NDW-based measures, and the results (Tables 34-35) revealed the lowest correlations were between NDW and NDW-50 in both essays (τb = .210 in Essay 1 and τb = .243 in Essay 2). These findings suggest that NDW might be the most useful index of all general word variation measures, at least for the present data.

Table 33: Correlations between lexical variation based on NDW-related measures and IELTS Writing Task 2 performance

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

Table 34: Correlations among measures of NDW-based lexical variation in Essay 1

**. Correlation is significant at the 0.01 level (2-tailed).

Table 35: Correlations among measures of NDW-based lexical variation in Essay 2

**. Correlation is significant at the 0.01 level (2-tailed).

As seen in Table 36, lexical diversity based on general word types did not correlate with the quality of the writing performance in both essays when it was measured by TTR and LogTTR. However, CTTR and RTTR were positively linked with the lexical score and the overall score in both essays, though the correlations were weak, τb = from .259 to .330. The remaining TTR-related measures of lexical variation show mixed results, with MSTTR having a positive weak correlation with lexical performance only in Essay 2 (τb = .215), UBER with vocabulary scores in both essays (τb = .192 in Essay1 and τb = .201 in Essay 2), and VocD with both lexical and overall band scores only in Essay 2 (τb = .245 and τb = .214 respectively). Additional correlation tests were run among the TTR-based measures and the results (Tables 37-38) recorded the lowest correlations to be between CTTR and TTR and between RTTR and TTR, τb = .443 for both in Essay 1, and τb = .441 and τb = .440 respectively in Essay 2. The other correlations among the TTR-based measures were from moderate to strong or perfect. These findings suggest the two corrected versions of TTR, namely CTTR and RTTR could be the most useful measures of general word type variation, at least for the scripts in the present study.

Table 36: Correlations between lexical variation measured by TTR indices and IELTS Writing Task 2 performance

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

Table 37: Correlations among measures of TTR-based lexical variation in Essay 1

**. Correlation is significant at the 0.01 level (2-tailed).

Table 38: Correlations among measures of TTR-based lexical variation in Essay 2

**. Correlation is significant at the 0.01 level (2-tailed).

With regards to lexical word variation, the results (Table 39) show that SVV1 and CVV1 significantly correlated with the overall IELTS band score and lexical score in both essays, and the correlations were positive, but weak (coefficients τb ranging from .20 to .371). The other measures in this group correlated weakly and selectively with the lexical score and the overall performance, and there were more significant positive correlations in Essay 1 than in Essay 2. This indicates SVV1 and CVV1 were useful indices to measure lexical word variation for the present data. Correlation tests were further conducted among measures of lexical word variation and the results (Tables 40- 41) demonstrate that among the measures that share the same denominator $( \Nu _ { \mathrm { { \vert e x } \mathrm { { \rangle } } } } )$ , NV had the strongest correlation with the general lexical word variation, LV in both essays. For example, in Essay 1, coefficients were the strongest between LV and NV (τb = .760), followed by between LV and AdjV (τb = .508) and between LV and VV2 (τb = .336), and between LV and advV $( \tau \mathrm { { b } } = . 2 4 7 )$ . In Essay 2, NV significantly correlated with LV $( \tau \mathrm { b } = . 7 7 2 )$ , and the correlation was the highest of the other indices, AdjV (τb = .389), VV2 (τb = .341), AdvV (τb = .246), and AdjV and AdvV combined (ModV, τb = .466). The findings suggest that the Vietnamese IELTS learners used more different noun types than other word part variation. Note that noun variation had a trivial significant correlation with the overall writing performance in Essay 1 only (τb = .204) and no significant correlation between NV and the writing performance in Essay 2 (Table 39).

Among the most useful measures of lexical richness across groups, NDW (τb = from .302 to .378) had the highest correlation with the overall band score of all lexical variation measures (CTTR/RTTR: τb = from .259 to .295; SVV1/CVV1: τb = from .201 to .371; SVV/CVV1: τb = from .201 to .371) and sophistication measures (VS2/CVS1: τb = from .170 to .215). In other words, lexical variation measured by NDW appeared to influence the total band score the most.

Table 39: Correlations between lexical variation based on TTR of lexical word parts of speech and IELTS Writing Task 2 performance

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

Table 40: Correlations among measures of lexical variation based on TTR of word parts of speech in Essay 1

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

Table 41: Correlations among measures of lexical variation based on TTR of word parts of speech in Essay 2

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

In brief, the findings revealed lexical density did not have an impact on the writing performance, and the different measures of lexical sophistication and lexical variation yielded different results. Among measures of lexical sophistication, VS2 and CVS1 were the most useful. For lexical variation, NDW and CTTR/RTTR were useful indices of general word lexical variation, and two transformed versions of verb variation, SVV1 and CVV1 were the most useful among measures of variation of lexical words. Of all lexical variation measures, NDW had the strongest impact on the overall writing quality (overall band score).

4.2.4 RQ4: How do lexical density, lexical sophistication and lexical variation correlate with each other?

As we aimed to explore the relationships between lexical density, lexical sophistication and lexical variation, following Lu (2012), we selected two groups of measures to run correlations. Group 1 (Table 42 and Table 43) has measures which all involve the use of total lexical words (LD, LS1, LS2, NDW, NDW-ES50, CTTR, D, and LV); Group 2 (Table 44 and Table 45) includes three verb sophistication measures (VS1, CVS1, VS2) and four verb variation measures (VV1, SVV1, CVV1, VV2).

The results (Table 42 and Table 43) show that lexical density had significant but low to trivial correlations with lexical variation (NDW-ES50, τb = .340) and D, τb = 188), and with lexical sophistication (LS2,τb = .161) in Essay 1. However, lexical density had no significant correlation in Essay 2 with lexical variation, though there was a significant weak link with lexical sophistication (LS1, τb = .245; LS2, τb = .213). LS1 and LS2 significantly correlated with all the NDW-based measures of lexical variation, but the correlations were weak in both essays, except slightly moderate with CTTR (τb = .459) in Essay 1.

Regarding verb sophistication measures (VS1 and CVS1), Table 44 and Table 45 show that VS1 had weak correlations with all the other verb variation measures (τb = from .246 to .326 in Essay 1; from .259 to .449 in Essay 2), so did CVS1 (τb = from .262 to .338 in Essay 1; τb = from .302 to .389 in Essay 2), and VS2 (τb = from .271 to .337 in Essay 1; τb = from .302 to .387 in Essay 2). The results here together with the earlier findings suggest that lexical density, lexical sophistication and lexical variation could measure three different aspects of lexical richness.

Table 42: Correlations among general measures of lexical density, lexical sophistication and lexical variation in Essay 1

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

Table 43: Correlations among general measures of lexical density, lexical sophistication and lexical variation in Essay 2

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

Table 44: Correlations among measures of verb sophistication and verb variation in Essay 1

**. Correlation is significant at the 0.01 level (2-tailed).

Table 45: Correlations among measures of verb sophistication and verb variation in Essay 2

**. Correlation is significant at the 0.01 level (2-tailed).

4.2.5 RQ5: What lexical errors do Vietnamese IELTS learners make in their IELTS Writing Task 2 performance?

This study also explored the lexical errors that Vietnamese IELTS learners committed in their IELTS Writing Task 2 essays. In total, there were 1272 lexical errors in Essay 1 and 1227 in Essay 2. On average, learners made about 15 mistakes in lexical words in Essay $1 ~ ( \mathsf { M } = 1 4 . 8 4 , \mathsf { S D } = 8 . 5 8 )$ , and about 14 in Essay $2 \left( \mathsf { M } = 1 4 . 2 8 , \mathsf { S D } = 8 . 7 5 \right)$ . It is important to note that there was marked variation among learners in their misuse of lexical words (large standard deviations).

The results also show that Vietnamese IELTS learners made slightly more lexical errors in Essay 1 than Essay 2. The results of a Wilcoxon signed-rank test show no significant difference in the average number of lexical errors committed between the two essays, Z = -689, p = .491, though they reported in the questionnaire that the topic of Essay 1 was more difficult than that of Essay 2 (see Section 4.2.1.2).

Table 46 presents the descriptive statistics for the different types of errors learners made in their IELTS Task 2 written scripts. Erroneous use involving spellings, verb forms, collocations, noun inflections and individual word choice made up the large majority of errors. They accounted for 23%, 18.6%, 15.6%, 13.7% and 11.5% of the total errors in Essay 1 respectively, and 20.9%, 20.2%, 15.8%, 13% and 9.5% of the total errors in Essay 2 accordingly.

Learners also committed other types of errors, though at a lower frequency. These included misuse of parts of speech (6-7%), misuse of copula be (about 5%), and redundancy (3.5-3.9%) in their order of frequency. Misaffixation, sentence litera translation, misuse of adjective inflections and misordering occurred, but very infrequently. Notably, there was considerable individual variation (large standard deviations) in all categories of errors.

Table 46: Descriptive statistics for lexical errors by type

The sub-errors in each of these most common groups of errors are presented in Table 47. It was notable that of the non-targetlike instances of verb forms, inappropriate use of the inflectional -s that marks the third-person singular (3SG-s) was the most common, accounting for 39.2% and 36.3% (of which largely was omission of it, 32.9% in Essay 1 and 30.6% in Essay 2). Alternating -ed/-ing/to- infinitive form of non-finite verbs was the next common, accounting for 29.5% and 23.4% of the total erroneous verb-related instances in Essay 1 and Essay 2 respectively. Incorrect verb-after-verb form, incorrect verb form after a modal verb/a preposition and inappropriate past participle forms also occurred, though not very frequently.

Regarding the errors related to noun inflections, the Vietnamese IELTS learners mostly omitted the inflectional morpheme -s that marks plural countable nouns, 73% and 47.8% of the time in Essay 1 and Essay 2 accordingly. They also used it in non-obligatory contexts (19% in Essay 1 and 18.2% in Essay 2). About one-third of the lexical errors involved learners alternating between countable and uncountable nouns in Essay 2, while 8% was observed in Essay 1.

In terms of individual word choice, confusing words with similar meanings such as comfortable or convenient were the most problematic for learners as they made more than 40% in the total erroneous instances related to word choice in both essays. Next most common was use of words with unclear intended meaning (24% and 17.2% in Essay 1 and 2 respectively). Learners also used inappropriate words with similar forms/ sounds (e.g., communicate / community) or with inappropriate derivative forms (e.g., productions / products), literally translated words from Vietnamese (e.g., cow meat / beef), and made other errors, at a low proportion though.

Table 47: Major lexical error types and sub-types

Concerning collocational use, incorrect prepositions that collocate with verbs/adjectives/ nouns (27.3% in Essay 1 and 23.7% in Essay 2), wrong collocates in fixed phrases (e.g., on conclusion) (25.7% and 26.8% in Essay 1 and Essay 2 respectively) and wordby-word translation (16.7% in Essay 1 and 14.9% in Essay 2) were more frequent than other collocational errors.

Due to the low frequencies of the other types of lexical errors, comparisons were made between the two essays for i) misspellings of general words and lexical ones, ii) misuse of verb forms, iii) misuse of collocations, iv) misuse of noun inflections, and v) misuse of individual word choice.

Misspellings were the most frequent type of error committed. As seen in Table 48, there were 373 misspellings in Essay1 and 288 in Essay 2. On average, learners misspelt about four general words and about three lexical words in their writing in Essay 1, and about three words for both types in Essay 2. Since the data were not normally distributed, the non-parametric Wilcoxon signed-rank test was conducted to compare the means of misspellings between the two essays. The results show more misspelt words in Essay 1 than Essay 2, Z = -2.462, p = .014, but the number of misspelt lexical words was not significantly different in the two essays, Z = -1.085, p = .278.

For the remaining major categories of error, the results of a number of Wilcoxon signedrank tests for non-normally distributed data show no statistically significant differences between the two essays in all these major categories of lexical errors (Table 49). In other words, the writing tasks did not influence the extent of lexical errors committed.

Table 48: Misspellings in IELTS Writing Task 2 performance

Table 49: Major error types across essays

*The Bonferroni correction for multiple tests was applied, so the alpha value for the Wilcoxon tests was adjusted to .05/4= .0125.

4.2.6 RQ6: How do lexical errors relate to the quality of the IELTS Writing Task 2 performance?

The study also explored the correlations between lexical errors and the writing performance. The results of the Kendall’s tau_b correlation tests for non-normality of data (Table 50) further show weak to moderate negative correlations between lexical errors and the lexical score and overall band score in both essays, p < .01. In other words, the more lexical word mistakes the learners made, the lower scores they tended to achieve. Compared with the other lexical measures (lexical density, lexical sophistication, and lexical variation), lexical errors (from τb = .385 to τb = -.427) had the highest correlation with the overall score, though negative, suggesting they might influence the quality of the writing performance the most.

With regards to misspellings, Table 50 further shows that general misspellings and misspelt lexical words negatively correlated with the overall band scores and lexical scores in both essays. Though the correlations were all weak, given the multiple factors that can have an influence on writing performance, this finding might suggest that the more spelling mistakes the learners committed, the lower scores they achieved.

For the remaining error types of lexical words, the results of the Kendall’s tau_b correlation tests (Table 51) show that misuse of parts of speech and incorrect verb forms negatively correlated with both lexical score and overall score in both essays. There were significant negative correlations between i) use of incorrect inflectional forms marking plural nouns, ii) between inappropriate individual word choice, and iii) between sentence literal translation and the lexical score and the total score in Essay 1, but not in Essay 2. On the contrary, collocational errors and the other error categories were associated with low scoring in vocabulary and overall performance only in Essay 2. These correlations were all weak, except a moderate negative correlation between erroneous use of parts of speech and lexical performance (τb = -.500) and overall writing ability (τb = -.417) in Essay 1.

Table 50: Correlations between lexical errors, misspellings and the writing performance

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed)

Table 51: Correlations between error categories and the writing performance

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

4.2.7 RQ7: How does the overall writing performance relate to lexical resource, task achievement, coherence/cohesion and grammatical range/accuracy?

Table 52 presents the Kendall’s tau_b (τb) correlation results, showing that all correlations were statistically significant, and with large effect sizes. Notably, lexical resource did not have the highest correlation with the overall band score in both essays, suggesting lexical use was only one of the dimensions determining the score of an IELTS Writing Task 2 script. In both essays, grammatical accuracy had the greatest/ second largest effect size. Correlation values tended to be higher in Essay 1 for all the criteria than in Essay 2, implying that how each sub-criterion contributed to the overall score might depend on the essay topic/task.

Table 52: Correlations between the overall band score and sub-scores

*. Correlation is significant at the 0.05 level (2-tailed). **. Correlation is significant at the 0.01 level (2-tailed).

5. SUMMARY AND DISCUSSION

5.1 Part 1: Learners’ perceptions of IELTS Writing Task 2 and their lexical self-efficacy

5.1.1 Reasons/Motivations for learning IELTS

The questionnaire findings show that learners reported learning IELTS for a variety of reasons. The most mentioned reason was to generally improve their English proficiency and seek better work opportunities. About half of the respondents reported pursuing IELTS to meet the requirements upon graduation from university in Vietnam, to seek overseas scholarships and obtain an internationally-recognised English proficiency certificate. These reasons appear legitimate, given that a large majority of the Vietnamese IELTS learners in the survey were lower and upper secondary school students and university students. The findings do not corroborate other studies. For example, Iranian learners in Sari and Mualimin’s (2021) study were more driven to learn IELTS for overseas studies, as 80% of them reported learning IELTS to seek foreign scholarships. In Chapelle et al.’s (2019) study, more than half of the IELTS test-takers took IELTS for immigration-related purposes. The greatest motivation underlying the learners in Coleman et al. (2003) was to secure university entry. In the context of IELTS becoming a hot trend in Vietnam as it could be used a passport for university admission (Phapluat, 2022; Vietnamnet, 2021), it is interesting to note that to be admitted to undergraduate programs in Vietnam was not a target of learning IELTS for this group of learners. Perhaps the national English Grade 12 graduation/university entrance examination could be too easy for these learners to equate it with an IELTS certificate, and instead they aspired for other purposes, though mixed, which could be due to the mixed sample of IELTS learners in our study. Its different result from the other research was additionally because these Vietnamese IELTS learners were preparing for IELTS in an off-shore campus in their home country, while in Chapelle et al.’s (2019) study, the participants were those who had taken IELTS and were now located in the host country. The social context could play a role in mediating individuals’ reasons for participating in a language test (McNamara, 2001).

In the present study, the learners recounted being motivated to learn IELTS for both its accessibility and credibility, though to a greater extent for the latter. Their positive perception of IELTS as a reliable measure of English proficiency found support in other research (e.g., Moore, Mahony, & Stroupe, 2012; Silalahi, 2014) and was in line with the widely acknowledged credibility of IELTS in the world (IELTS, 2021a). IELTS test-takers in Chapelle et al.’s (2019) study also had a positive attitude towards IELTS. Positive conceptions of access to the IELTS test and IELTS materials reported in the present study, on the one hand, reiterate learners’ interest in the IELTS test and their preparation for it. On the other hand, the finding implies the popularity and influence of IELTS (Pearson, 2019) and an advantage for IELTS learners in terms of more readily available IELTS materials through different channels, as these learners reported.

5.1.2 Factors influencing IELTS Writing Task 2 performance

With regards to task-related factors, topic unfamiliarity was perceived as the greatest barrier for these Vietnamese IELTS learners, a finding also observed in Iwashita et al. (2021) and Moore et al. (2012). In the present study, the difficulty related to topic novelty received more unanimous agreement than topic disinterest. This could be explained by the fact that IELTS Writing Task 2 is “the topic-driven, rhetorically discursive style required” (Pearson, 2019, p. 201) and an unfamiliar topic is thus cognitively demanding (Coxhead, 2018). Yet, with its topic-driven nature, IELTS Writing Task 2 could allow idiosyncratic realisations of the task, and so could be subject to individual experiences. It is understandable that time pressure and no reference to external resources were additionally identified among top task-related obstacles, which find support in prior studies in which time constraint was most often cited as challenging (e.g., Gardiner & Howlett, 2015; Pearson, 2019).

Of the linguistic factors, the learners reported vocabulary to be the most difficult, which partially confirms previous research showing vocabulary and grammar were the two most problematic areas for EFL students (Bulqiyah et al., 2021; Chen, 2002; Lam et al., 2020) and IELTS learners (Maharani & Setyarini, 2019). However, the findings here somewhat differ from those in Enneifer’s (2021) study which identified spellings and grammar to be the most challenging and in Peloghitis’ (2016) with Japanese EFL students reporting the most demanding aspect to rest in the rhetoric style of the argumentative writing. It is interesting that in Nguyen and Nguyen’s (2022) research, vocabulary was not among the five most mentioned challenges by Vietnamese IELTS learners in Ho Chi Minh City. The difference could be due to the differing writing experiences and extents of IELTS Writing Task 2 exposure/familiarity and practice by different groups of learners in different contexts. This is understandable, as in the open-ended free IELTS Writing Task 2, meaning-making governs lexical choice and lexis carries most meaning (Schmidt, 2001). Yet, the finding points to the need to have different forms of support and preparation that respond to learners’ needs to enhance their writing self-efficacy and performance (see Section 6.1).

The Vietnamese IELTS learners in the present study reported a higher level of selforiented anxiety than examiner-oriented anxiety; the former was sourced from their own over-occupation with the quality of their writing in terms of task response, timely task completion, and meaning expression in English, a lack of practice and fear of low scoring. Fear of being rated lower for their errors was a most strongly-felt form of examiner-oriented anxiety. The level of examiner-oriented anxiety related to examiners’ negative evaluation of their writing, appropriate academic writing style and comprehensibility was also intense, although lower than anxiety about errors. Such findings indicate that these learners were perhaps more worried about examiners judgement of the linguistic dimension of their writing performance than other aspects. This could be possibly attributed to their low level of confidence or a lack of self-trust in the linguistic competence on the learners’ part. The findings agree with prior research indicating that learners’ worry associated with writing arose more from the linguistic dimension than the content aspect (e.g., Cheng, Horwitz & Schallert, 1999; Hertz-Lazarowitz & Bar-Natan, 2002). Fear of poor evaluation was also reported in other research (e.g., Abdel Latif, 2012; Rezaei & Jafari, 2014). For example, Abdel Latif (2012) found similar results with Egyptian EFL learners who reported fear of negative comments from examiners, and their linguistic level and performance were among the sources of anxiety. Anxiety due to overt concerns about raters’ negative judgement is what Bandura (1986) termed cognitive anxiety, which could be counterproductive to the motivation to write and writing quality. A lack of studies on writing anxiety associated with IELTS Writing Task 2 prevented more accurate comparison with other similar studies.

Perceived writing anxiety, both self-oriented and examiner-oriented anxiety, was not significantly linked to the lexical and overall writing performance of both essays. Such a finding does not resonate with some previous research which found a significant negative correlation between anxiety / apprehension and writing performance (e.g., Erkan & Saban, 2011; Limpo & Alves, 2017). Yet, it echoes the finding by Lee (2005) that self-reported anxiety was not associated with writing performance by Taiwanese EFL students. One reason could be that self-perceived anxiety did not mirror the learners actual ability. Another interpretation could be that writing anxiety “may play a role only when the task is at the edge of one’s writing competence” (Lee, 2005, p. 360). The two IELTS writing tasks in the present study, though perceived as difficult by the learners (and Essay 1 was more difficult than Essay 2) were perhaps not prohibitively challenging for this group of learners. Another plausible reason could be because the survey measured the perceived anxiety involved in IELTS Writing Task 2 in general, while the IELTS Writing Task 2 performance in each essay was based on a specific task with a specific topic. A lack of parallelism between perceptions of anxiety and writing scores suggests the need to research the construct of writing anxiety in task-specific contexts. In addition, writing anxiety is an affective aspect (Lee, 2005; Teng, et al., 2017) that is subject to students’ backgrounds and their individual writing experiences, which could well be an added factor.

Another important finding was that the learners reported being indirect in their IELTS Task 2 writing, which is consistent with Hinkel’s (1997) study uncovering that Asian non-native writers of English tended to be more indirect than native counterparts. The finding is also in line with Xi and Guang’s (2007) study where Chinese EFL learners, due to cultural influence, were inexplicit, ‘beating around the bush’ in their English writing, which was often devoid of a clear thesis statement. Many Vietnamese IELTS learners in the present research recounted employing literal translation in writing IELTS Writing Task 2. Literal translation was a type of raw meaning-form mapping that might entail non-target language use, and it was one of the lexical error types in the present study (see Section 2.4.6). Other research (e.g., Sung & Wang, 2020; Wang & Bai, 2017) found that EFL learners thought and shaped up ideas in L1 and then mapped the ideas out to the target English forms. This kind of L1 transfer is not new in light of the fact that an L2 learner has an existing L1 system to draw on as they write in an L2 (Llach, 2011). Their L1 could become an additional useful resource as “learning to write in a second language is one of the most challenging aspects of second language learning” (Hyland, 2003, p. xiii). However, an over-reliance on L1 to make meanings might be harmful and lead to errors.

5.1.3 Lexical self-efficacy

It is worth noting that these learners reported a particularly low lexical self-efficacy with regards to spelling lexical words correctly. While knowing how to spell a word is part of knowing it (Nation, 2013), viewing misspelling a form-related issue might be, at first glance, alarming. However, writing an IELTS Writing Task 2 essays involves language use in context where meaning expression is overriding. It is very different from discrete language exercises that focus on linguistic forms; upon closer scrutiny, the challenge would be understandable in the unpredictable nature of the writing topic of an IELTS Writing Task 2 (Wilson, 2010). It is this topic unpredictability that might involve unknown lexical items or partially known words that learners were not certain about in their written form.

Another important finding was the positive but weak correlations between the lexical self-efficacy reported by the learners who wrote the two essays and their IELTS Writing Task 2 performance in terms of the lexical resource score and the overall score in both essays. The findings here disagree with other studies showing self-efficacy and writing performance were closely linked (e.g., Golparvar & Khafi, 2021; Zhang & Guo, 2012).

The weak correlations might suggest learners’ perceptions of their lexical self-efficacy and writing performances are two different constructs.

Indeed, the former was about learners’ perceptions of their productive lexical knowledge based on Nation’s (2013) framework, but perceptions were arguably not actual performances. Self-reported data could be a measure of ‘offline’ lexical knowledge (Godfroid, 2020), while lexical scores reflected lexical use in real-time communicative writing that is context- and task-bound. Moreover, lexical resource was among the multitude of factors that affected the IELTS Writing Task 2 score. Having said that, given the small sample of learners writing the two IELTS Task 2 essays (86), the significant correlation, though weak, might suggest some possible impact of lexical self-efficacy on the writing performance that is worth further investigation.

5.2 Part 2: Performance-based lexical resource

With regards to performance-based lexical resource, four key themes will be discussed: i) impacts of writing tasks/topics, ii) relationship among quantitative lexical measures, iii) relationship between the quantitative measures, the quality of the writing performance, and iv) lexical errors and the writing quality.

5.2.1 Impacts of writing tasks/topics

The findings revealed an effect of writing tasks/ topics on the quantitative measures of lexical resource in IELTS Writing Task 2 performance by Vietnamese IELTS learners. Scripts about the topic of community work (Essay 2) contained denser and more sophisticated vocabulary (LS1) than those about living in a foreign country (Essay 1). The greater advantage in terms of lexical density associated with Essay 2 could be explained by the fact that learners perceived Essay 2 was significantly less difficul than Essay 1 and the topic of Essay 2 was more familiar/relevant than that of Essay 1, thus facilitating content generation. The finding echoes previous research showing scripts based on familiar topics induced more content words (e.g., Yu, 2010; Zheng, 2016). More sophisticated lexical words (LS1) in Essay 2 performance could be understandable. For the more familiar task on community service, learners broadly had more sophisticated words to encode their intended meanings. They used more sophisticated word tokens (LS1) overall, although not necessarily more sophisticated word types (LS2) or more sophisticated verb tokens (VS1, CVS1, VS2). In other words, the verbs used were comparably sophisticated for the two topics. Further analysis of what other lexical word parts of speech (e.g., sophisticated nouns/adjectives) made up sophisticated words in these learners’ essays would be useful. It is interesting that many IELTS learners in the present study explicitly mentioned ‘many on-topic words’, while a few students recounted how each task/topic enabled access to advanced or low frequency words. This could perhaps show that they prioritised attention to diversifying vocabulary used. While more research on learners’ writing processing is needed, generally, this finding corroborates other research showing topics that are relevant to learners also advantaged lexical sophistication (e.g., Lo & Hyland, 2007; Yu, 2010; Zheng, 2016). While success in IELTS Writing Task 2 involves multiple abilities rather than just topical knowledge (Cullen, 2017), the intensity of topic impact from the learners perspective should be taken into account.

The topic of community work (Essay 2) was advantageous in facilitating learners to use a wider range of general word types, selectively in terms of NDW-ER50, NDW-ES50, MSTTR and D value. The fact that learners reported they had more vocabulary to use when writing Essay 2 (community work) could have perhaps contributed to the greater level of lexical variation in terms of the number of different words. From a cognitive perspective, topic familiarity aided the generation of ideas, freeing up resources to attend to linguistic aspects, so as not to repeat words (Coxhead, 2018; Nation, 2013).

The findings generally agree with other research which found performances in familiar topics had a higher level of lexical diversity (e.g., Cho, 2019; Ryoo, 2018; Yoon, 2017; Yu, 2010; Zheng, 2016). Greater values of lexical word variation measures based on TTR of lexical word parts of speech (VV2, NV, advV, ModV) in Essay 1 could be understood as a mathematical calculation as the denominator (number of lexical words) of these ratios was larger in Essay 2. Essay 2 elicited more lexical words (M=160.48, SD=31.62) than Essay 1 (M= 150.08, SD= 33.99), Z= -3.544 (p<.001). By using a large set of measures, the present study has revealed that using the different indices of lexical variation could find different results that require prudent interpretation that necessitates considering the formula for calculating the indices used. The findings indicate that the four measures (NDW-ER50, NDW-ES50, MSTTR and D) showing significant effects are more reliable than other NDW-based measures (NDW or NDW-50) when the samples differ in length or are substantially longer than 50 words. NDW does not take into account length difference and NDW-50 looks at the first 50 words only, while NDW-ER50, NDW-ES50, MSTTR and D are better at modeling word usage throughout the essay while also controlling for sample-size effects.

While selective lexical measures differed between the two essays, the non-significant difference in the overall band score and lexical score between the two essays further suggests that lexical richness is more complex than the presence of sophisticated or diverse words. An effect for the writing task/topic was observed, though selectively in the lexical dimensions of lexical density, variation and sophistication. However, it is interesting that there was no significant effect for the writing task/topic on the total occurrences of lexical errors. This could be that errors are more related to learners existing lexical control and knowledge, and thus less subject to writing tasks/topics. The lexical errors learners made could indicate the most problematic areas of lexica use for this group of learners, as Thewissen (2013) noted, errors are “potential indicators of the developmental stages learners are likely to have reached” (p. 78).

5.2.2 Correlations between quantitative lexical measures

The present study revealed that the three quantitative dimensions of lexical density, lexical sophistication and lexical variation were not significantly correlated or only weakly correlated with each other. The findings are in line with previous research which showed no or weak correlations between these measures, suggesting they gauge different constructs, both in oral narrative performance (Lu, 2012) and written performance of other types (e.g., González, 2017; Laufer, 1994; Nasseri & Thompson, 2021). A tradeoff between lexical diversity and sophistication was even recorded in some studies (Verspoor et al., 2012; Yoon & Polio, 2016), which further reiterate that these measures could be completely different constructs.

The present study has shown that among the measures that share the same denominator (N ), noun variation (NV) had the strongest correlation with the general measure of lexical variation (LV) in both essays. This suggests that nouns made up the majority of lexical types in the present corpus. The finding contradicts Nasseri and Thompson’s (2021) study where there was no significant correlation between LV and NV in written abstracts, and Lu’s (2012) study finding that VV2 (verb variation) had the strongest correlation with LV in oral narrative performance. The differences in results could be due to the different writing genres and modes used to elicit the language production. In our study, the scripts were discursive argumentative essays where learners had to argue and support their position, so assumedly they had to supply many propositional ideas to develop argumentation. In oral narratives (Lu, 2012), verb types seem to be suitable to narrate actions or events that happened.

Different genres might influence personal preferences for how learners vary vocabulary (e.g., Li, 2000; Park, 2013). Perhaps it could be that these Vietnamese IELTS learners tended to use more different noun types than verb types, adjective types, and adverb types, since nouns could be easier to recall and access for them in real-time writing or perhaps these learners had as many lexical words as nouns in their lexical repertoire. These are speculative insights and further research is needed to explore possible typical patterns of using lexical words in written language production by Vietnamese EFL learners. For now, the findings point to the usefulness of using multiple measures of lexical variation, as they provide more diagnostic information about the use of lexical words in IELTS Writing Task 2 performance.

5.2.3 Correlations between quantitative lexical dimensions and the quality of the writing performance

The present study has shown that lexical density significantly negatively correlated with the lexical score and overall band scores in Essay 1, though these correlations were negligible and weak; no significant correlations were found in Essay 2. The findings are in accord with those of prior research with oral narratives (Lu, 2012) and with written texts, for example source-based scripts (Maamuujav, 2021) and written abstracts (Nasseri & Thompson, 2021). This suggests that the presence of content words does not affect the band score of the writing performance irrespective of the production mode (oral vs. written) and type of writing. In fact, lexical density “is a measure of information in any passage of text, according to how tightly the lexical items have been packed into the grammatical structure” (Halliday & Martin, 1993, p. 76, italics added). This could imply that a different level of lexical density might just reflect how the individual learner elects to pack their content in structural forms. Obviously, the outcome of the writing depends on many other factors, namely how well they use these content words (lexica accuracy), connect ideas and use grammar structures, among others.

In the present study, of all the lexical sophistication measures, the two verb sophistication indices (VS2, CVS1) correlated with the writing scores in both essays. This might suggest these corrected verb measures better capture what the IELTS raters attended to regardless of the writing topics. Though selective measures of lexical variation had positive weak correlations with the writing performance score, the lexical variation correlations were stronger than the other two measures, lexical sophistication and lexical density. This suggests, of the three quantitative lexical dimensions, at least, diverse vocabulary might have a stronger impact on the quality of writing. González (2017) also found lexical diversity has a stronger link to the quality of the writing than use of advanced words. However, in Maamuujav’s (2021) study, diversity did not contribute to the quality of the writing (text-based essays) by Spanish L1 writers of English, but sophisticated words measured by academic words did. The findings of the present study slightly do not echo other L2 research which reported a stronger positive correlation between lexical variation and scores (e.g., Crossley et al., 2014; Engber, 1995; Jarvis, 2002; Yu, 2010).

The results here also seem to contradict what was found in research on IELTS writing: that lexical variation and sophistication strongly predicted the writing performance (Banerjee, et al., 2007; Barkaoui, 2016; Riazi & Knox, 2013). This could be due to the different measures used in our study and these IELTS studies and the different writing task prompts / topics used to elicit scripts. We used multiple measures of lexica variation, while Barkaoui (2016) relied on MTLD to gauge lexical variation and others (e.g., Banerjee et al., 2007; Riazi & Knox, 2013) used the one index of TTR. In Riazi and Knox (2013), the data set of 270 scripts were test-takers’ responses to 26 different tasks. Scripts in Banerjee et al. (2007) were based on multiple different tasks and in Barkaou (2016) were repeated performances of different topics of IELTS Writing Task 2.

This could further confound the results, given the current empirical knowledge on the potential effects of task topics as shown in the present research and others (e.g., Ryoo, 2018; Yoon, 2017; Yu, 2010). This variation makes it even more challenging to compare findings across studies.

It is interesting to note that while noun variation (NV) correlated most strongly with the lexical variation of the measures based on lexical word parts of speech in the present study, it did not have the highest correlation with the quality of the writing, but verb variation (SVV1/CVV1) did. However, NDW, CTTR, RTTR had higher correlations, and NDW the highest, which could well suggest at least raw measures of lexical variation such as NDW might more closely reflect the range of vocabulary that at least the IELTS raters in general looked at in the present scripts, independent of the writing topic. In fact, NDW would likely be strongly correlated with essay length (since it does not control for sample size), and it is known to have a strong correlation with writing scores (e.g., Kim, 2014; Wood et al., 2019). Raters tend to reward longer essays (better fluency, more content) (e.g., Kobrin, et al., 2007; Guo et al., 2013). At the same time, the findings of the present study suggest that some features of lexical variation (e.g., CTTR, RTTR, SVV1/ CVV1) achieve better consistency in capturing a construct attended to by raters. Given many other factors could be at play, more research is needed to analyse the quality of use of the different categories of lexical variation.

5.2.4 Lexical errors and IELTS Writing Task 2 performance

5.2.4.1 Prevailing errors

The findings on lexical accuracy have shown that the Vietnamese IELTS learners committed many types of lexical errors, of which misspellings, misuse of verb forms, collocations, noun inflections and word choice were the most common in the two IELTS Writing Task 2 essays. The findings broadly resemble prior research on IELTS writing (Bagheri & Riasati, 2016; Divsar & Haydari, 2017; Sanavi, 2014) and on EFL writing (Ander & Yildirim, 2010; Chan, 2010; Lee, 2020; Li, 2015; Mohammadi & Mustafa, 2020) which found misspellings, word choice, verb forms, collocations were among the most frequent lexical errors, though the order of their frequencies varied in differen studies. For example, that misspellings topped the list of lexical errors finds support in Lee (2020), Li (2015), Llach (2007) and Pouladian, et al., (2017), but not in others (e.g., Ander & Yildirim, 2010; Hemchua & Schmitt, 2006; Picot, 2017; Sanavi, 2014) where word choice was the most erroneous. The different L1 backgrounds of the learners involved in these studies could account for the different issues they encountered. As learners learn an L2, they presumably draw on their existing L1 system (Llach, 2011; Schoonen & van Vuuren, 2021), which potentially influences their lexical use, especially in IELTS Writing Task 2, a free meaning-driven act.

In the current study, about one-fifth of the lexical errors were misspellings, and nearly such a proportion involved misuse of verb forms, which was substantial, and deserves attention. It is worth noting that omission of the inflectional morpheme -s that marks the third-person singular present tense and the plurality of countable nouns was quite common. One explanation could be related to Vietnamese L1 as an isolating language which does not have an equivalent inflectional system to mark subject-verb agreement or noun plurality (Ngo, 2001). Though speculative, this is likely, drawing on research that has shown L1 influence in the case of inflectional omission (e.g., Jiang, Novokshanova, Masuda, & Wang, 2011; Lee, 2020; McDonald, 2000; Siemund & Lechner, 2015) and the challenge was due to a lack of congruence in the target language feature between learners’ L1 and the target language. For example, Lee (2020) found omission of noun inflections constituted the large majority of morphological errors in EFL writing by Korean learners of English, as noun plurality is optional in Korean L1. Coupled with i) the low communicative value of the morphological inflection -s as an indicator of verb singularity and noun plurality and ii) the pressure of a timed IELTS Writing Task 2 performance, access to this inflectional form -s might be just “blocked” to prioritise

attention to meaning over form (Goldschneider & DeKeyser, 2001), though the learners might well have explicitly learnt it as one of the basic grammar points during school years in Vietnam.

The other common lexical errors were related to inappropriate word choice and collocational use. Misselection of words with confusing meanings or near synonyms and words with unclear meanings made up a majority of word mischoice. Word mischoice was not the most frequent type, as reported in some previous research on IELTS writing (e.g., Divsar & Haydrai, 2017; Picot, 2017; Sanavi, 2014) and on general EFL writing (Ander & Yildirim, 2010; Chan, 2010; Hemchua & Schmitt, 2006; Mohammadi & Mustafa, 2020). For example, Hemchua and Schmitt (2006) and Picot (2017) reported near synonyms and semantic word selection to be the most common in the two studies with Thai and Greek learners respectively. Yet, the findings of the present research echo these prior studies by showing that word choice was a major challenge for learners.

Collocation errors mostly involved the Vietnamese learners’ misuse or omission o prepositions collocated with a lexical word and misuse of fixed phrases. Such a finding supports some previous research which found use of prepositions was also challenging to Egyptian learners (Gibriel, 2020), to learners from Iran, Pakistan and China (Mohammadi & Mustafa, 2020) or as one fixed part in collocations to Malaysian learners of EFL (Hong et al., 2011).

The erroneous use of word choice and collocations could be caused by inter-lingual and intra-lingual factors. It is likely that the Vietnamese learners in the present study resorted to translating their ideas from Vietnamese into English in writing. Numerous instances of inappropriate use of prepositions / word choice were related to the mismatched expressions between Vietnamese L1 and English L2. For example, in Vietnamese a preposition is required after the verb ‘thảo luận’ (discuss) while in English, it is not. This might have led to the error in ‘discuss about [O/] environment’ [thảo luận về môi trường]. In some other instances, “làm” in Vietnamese could correspond to many English words with different meanings and usages, which could be a likely cause of L1-induced errors which were evident in “doing [working] for a charity organization … [làm cho một tổ chức từ thiện] and in “They make [do] some charity activities” [làm các hoạt động thiện nguyện.]. The “asymmetries between the L2 lexical item and the L1 concept or schema onto which it is mapped give rise to lexical errors” (Llach, 2011, p. 18). L1 Vietnamese influence could be a source of errors, as other studies found a majority of the collocational errors in their studies were L1-based (e.g., Hong et al., 2011; Laufer & Waldman, 2011; Nesselhauf, 2003; Shitu, 2015). However, synonyms only work in context, and appropriate use of lexical items requires understanding of its constraints of use (Nation, 2013) and acquiring collocations is one of the major hurdles for EFL learners (Peters, 2016), so the errors that learners committed could possibly indicate their inadequate knowledge or a lack control of the written English vocabulary that they wanted to use. For example, the inappropriate verb collocating with the noun ‘awareness as in “advance [enhance/promote] their awareness” and the incorrect preposition as in “good in [at] English” was not related to L1 Vietnamese, but rather it shows the learners did not know enough about these collocations.

5.2.4.2 Lexical errors and the writing performance

The negative correlation between lexical errors and the quality of the writing, though weak in both essays further shows lexical errors slightly influenced the quality of vocabulary use. This is in line with Llach (2007) who found lexical errors did not influence the quality of written compositions (i.e., communicative effectiveness) by Spanish primary school students. This might demonstrate inadequate control of the words in use or it could be mistakes under time pressure as they needed to complete their timed performances. It is not just about the presence of diverse or sophisticated words that count.

A closer look at the types of lexical errors further revealed interesting findings about the nature of lexical errors and the writing performance. In the present study, misspellings occurred frequently, accounting for about a quarter of the total errors. While this could be irritating for raters, a lack of strong link with the writing scores could mean that raters still understood the message related to these misspelt words. This is a tentative explanation until more understanding from the IELTS raters’ perspectives is revealed to understand whether the committed errors “cause some difficulty for the reader” o “impede communication” or “severely distort the message” (IELTS, 2021b, p. 21). Above all, as correctly spelling a word is part of the package of knowing the meaning of a word (Nation, 2013; 2020), misspellings could show limited or partial lexical knowledge on the part of the learners that needs pedagogical attention. Or they could be a slip of the pen due to hand-recording under time pressure.

It is interesting to note that though errors related to word form (parts of speech) occurred at a much lower rate, about 6% in Essay 1 and 7% in Essay 2, they appeared to have the strongest impact on the band scores, though from weak to medium size. It could be that misuse of these word forms exerted greater impact on the communicativeness of the script possibly because they were related to content words. Furthermore, errors related to word form is explicitly mentioned in the IELTS scoring rubric (IELTS, 2021b), which might have directed IELTS raters to attend more to errors with word form. Although misuse of verb forms was common, the correlation was weaker than word form errors, which could be attributed to raters perhaps viewing them more grammatically, and might have marked them down in the category of grammatical errors. In this regard, the often quite blurry distinction between vocabulary and grammar (Llach, 2011) is well taken. Yet, the frequent occurrences of erroneous verb form indicate this is a problematic area for this particular group of Vietnamese IELTS learners in the present study, as knowing a word also involves knowing “its grammatical patterns” (Nation, 2013, p. 27).

6. RECOMMENDATIONS AND CONCLUSIONS

Based on the findings of the present study, the following recommendations are made for IELTS, IELTS teachers and learners and future research.

6.1 For IELTS, IELTS teachers and IELTS learners

Understanding IELTS learners’ reported writing challenges, sources of anxiety, and their level of lexical self-efficacy would be a first step for IELTS teachers in their strategic planning to teach different groups of IELTS learners. As the learners identified inadequate practice to cause difficulties, it is important to provide learners with ongoing writing opportunities to engage in writings based on a variety of topics in the genre of IELTS Writing Task 2. Sufficient writing practice through instructional activities, self-learning and mock tests will help increase learners’ confidence about their lexical self-efficacy. To reduce fear of negative judgement from examiners, teacher feedback should be constructive, and built up with time since excessive correction could be emotionally taxing and lead to demotivation (Mahfoodh, 2017). As feedback is helpful for self-efficacy (Ruegg, 2018), it should also focus on what students can do, to enhance their confidence. The role of confidence in L2 writing is clear, as “positive self-efficacy can engender greater writing interest, stronger effort, and greater perseverance” (Teng et al., p. 2).

Since the “learning burden” of a word depends on many factors, among which are instructional materials (Nation, 2020), it is equally important for IELTS materials designers to take account of different aspects of productive lexical knowledge that are reportedly problematic for learners. It is worth taking into account different levels of lexical self-efficacy and providing differentiated feedback for different groups of learners, since Mendoza et al. (2022) found that students with a low self-efficacy expressed a need for support and feedback. Appropriate instruction that attends to the three components of experience, practice and feedback would help promote writing self-efficacy (Pajares, 2003).

IELTS Writing Task 2 designers should take into consideration the issue of topic difficulty/ familiarity that could potentially govern the lexical traits of the writing performance. That said, learners’ individual experience with different topics might vary; thus, increased exposure to topic-related vocabulary is important. Wilson (2010) proposes that topics “may be related to their [learners/test-takers’] own lives and experiences, but candidates also need to have some awareness of more general issues in order to cope well with Writing Task 2” (p. 220). IELTS teachers and learners should introduce / find a list of different words or sophisticated vocabulary related to a given topic. These topics could be sourced from different corpora for learners to prepare for their IELTS Writing Task 2. This is important, as the learners also identified topic unfamiliarity as one major barrier. As the present study has shown, lexical diversity was most impactful among the three quantitative measures (lexical density, lexical sophistication and lexical variation) on the IELTS band score, suggesting that greater pedagogical attention needs to be drawn to helping students to diversify their lexical items in writing. It would be helpful to introduce alternative ways of expressing similar meanings through related words, words of different parts of speech, synonyms, and understand their polysemous, multi senses, constraints of use.

Feedback should be organised to help learners remedy their lexical errors. Learners should be made aware of the different types of errors committed, and their prevalence to avoid repetition of errors and fossilisation either through instruction or self-learning. Further attention needs directing to lexical errors that have the highest correlation with the writing quality (i.e., misuse of lexical word parts of speech, misspellings). Explicit treatment of lexical errors that are due to L1 influence, such as patterns of literal translation, would further help, since L1 and L2 words might operate very differently, causing different ‘learning burdens’ (Nation, 2020) for different groups of learners.

While misspellings might be conceptualised as minor or mechanic issue, they might be consequential in high-stakes tests such as IELTS. Although the present study has shown a weak correlation between misspellings and writing quality, the significant correlation could mean something considerable among the many factors that affect the writing performance. Given that our Vietnamese IELTS learners reported a low self-efficacy in spelling lexical words correctly in writing, attention to orthographical issues in IELTS Task 2 writing is even more important. Recall that learners in the present study handwrote their essays under time pressure. As time constraint was identified as one source of difficulty, as well as learners’ self-oriented anxiety about their writing performance, practice in recording Task 2 responses in real test conditions would further help. Increased encounters with words through aural or textual input on different topics and explicit learning of orthography of words would be useful.

IELTS teachers can combine explicit teaching of lexical knowledge and task-based teaching, providing extended opportunities for learners to write, and put their lexical repertoire into use, to enhance their lexical self-efficacy. It would be useful to raise students’ awareness of what it means to know a word (Nation, 2013). Through writing, they can produce pushed output (Swain, 2005) to notice the gaps between what they have, what they need to use and what they are capable of using. Vocabulary learning and acquisition do not occur overnight, but need to be built up as an incremental ongoing endeavour (Nation, 2013). Productive lexical knowledge in IELTS Writing Task 2 is even more demanding of invested efforts from IELTS teachers, learners, and IELTS materials developers.

IELTS is renowned for its rigorous validation of tasks, and for its fairness as the link between the different aspects of lexical resource (lexical range, lexical sophistication, and lexical accuracy) and the writing score has been made explicit in the IELTS Writing Task 2 scoring rubric (IELTS, 2021b). The descriptors for these lexical aspects in the scoring rubric are user-friendly and intuitively easy to understand. However, while information about lexical errors in terms of quantity and quality (types of lexical errors in word formation, collocation, spelling, communication- impeding errors) is more explicitly stated, it is not sufficiently clear what it is meant by a wide or limited range of vocabulary or uncommon lexical items (Smith, 2019). As Bachman and Palmer (1996) argue, a good scoring rubric should be as explicit as possible in terms of the “abilities of interest” it is intended to measure. At this point, providing operational definitions of what to look for in terms of lexical range would also be useful to IELTS raters, teachers and learners. For example, it would be helpful to introduce different indices that are not too technical such as non-repetitive use of words (NDW, word types), or use of different verb/noun/ adjective/adverb types to IELTS raters in some form (e.g., annotation, training) so that they have more specific indicators to draw on in the process of marking. Annotations as to how to judge low frequency words (lexical sophistication), against which reference would also help.

6.2 For future studies

The present study employed Nation’s (2013) framework to collect information about Vietnamese learners’ perceptions of their lexical self-efficacy. However, this framework only measures lexical knowledge offline (Godfroid, 2020), so findings about perceptions of the learners’ self-efficacy might not mirror what actually occurred in the process of real-time written language production. It would be a fruitful avenue for future studies to use recall methods to track learners’ processing of putting their lexical knowledge into written productive use, to understand “how well learners can access their knowledge of different aspects of a word” (Godfroid, 2020, p. 435). Future research could also consider using factor analysis for the different constructs in the questionnaire.

By using a large set of measures of lexical resource, the present study has revealed some of the most useful measures of lexical sophistication and lexical variation, at least for exploring lexical richness in IELTS Writing Task 2 scripts by Vietnamese IELTS learners. Future research could use transformed versions of verb sophistication, VS2 and CVS1 to measure lexical sophistication. Of the 20 indices of lexical variation, NDW, CTTR and RTTR (two corrected versions of traditional TTR), SVV1 and CVV (two transformed versions of verb variation) would be useful considerations. These measures had the highest correlations with the lexical score and the overall band score in both essays. Although the correlations were weak, they deserve attention, as they could indicate what raters were interested in among the multiple factors that affected the quality of the writing. As EFL writing is a complex multi-dimensional act where many factors are potentially at play, it could be useful to consider using more sophisticated statistics tests in future studies of this kind.

The results of the present study underscore the necessity to investigate the possible effects of tasks / topics on lexical features of the writing performance. In this respect, it would be telling to explore learners’ experience of the task/topic as a complementary data source that provides useful explanatory power. The present study geared its interest more on exploring the topical impact than the effect of the variable of proficiency (different band scores). However, future research could examine how writing performances of different band scores differ in terms of lexical richness across topics. Furthermore, the effect of writing task / topic in the present study was exploratory, drawing on the differences in lexical measures between the two IELTS Writing Task 2 essays and learners’ perceptions. Future studies should consider adopting a more rigorous design.

Following Lu (2012), the present study defined sophisticated words / word types broadly as those beyond the first 2000 in the BNC list of 100 million words. As lexical sophistication deals with “selection of low-frequency words that are appropriate to the topic and style of writing, rather than just general, everyday vocabulary” (Read, 2000, p. 200), teasing out inappropriate use or errors related to these uncommon lexical items would be useful to further expand our understanding of lexical sophistication in written language production. With regards to lexical variation, information about qualitative analyses of the actual nouns, verbs, and adverb types used in the scripts would be telling in future research.

Future studies could examine prevailing lexical errors and their degree of gravity at different band scores and adopt more fine-grained analysis of patterns of misspellings. This would be useful to inform instructional feedback for this group of Vietnamese IELTS learners.

While how lexical inaccuracy affects communication/comprehension is described alongside other descriptors in the IELTS Writing Task 2 scoring rubric (IELTS, 2021b), it is not clear how IELTS raters looked for incomprehensibility in judging lexical errors in the scripts of the present study. Understanding raters’ perspectives, how they judge and mark down for lexical errors would be insightful to enhance interrater reliability and help test-takers better prepare for their IELTS Writing Task 2 performance.

6.3 Conclusions

Our study is one rare study that has explored lexical resource in IELTS Writing Task 2 performance from both learners’ perceptions and analysis of their performance-based lexical richness. The combination of learners’ perspectives, quantitative lexical measures (lexical density, lexical sophistication, and lexical variation) using a large set of 26 indices and qualitative analysis of lexical errors has provided rich and useful insight into lexical use by IELTS learners in real IELTS-learning contexts in Vietnam. The implications of this study could be useful beyond the particular context of Vietnam to benefit IELTS learners in other similar settings in regard to how to identify sources of IELTS writing Task 2 difficulty and enhance lexical use in IELTS writing Task 2 performance.

ACKNOWLEDGEMENTS

The researchers would like to thank the following organisations / individuals for their support:

• IDP: IELTS Australia for funding this research project
• University of Foreign Languages, Hue University for supporting Trang, Binh and Nhu to undertake this research project
• Ms Jenny Osborne, Ms Stephanie Bethencourt and Mr Vincent Blokker (IDP: IELTS Australia) for their wonderful companionship, mentorship and timely assistance during the execution of this project
• Vietnamese IELTS learners who participated in this research and the IELTS teachers who facilitated the collection of data
• Professor Xiaofei Lu from the Pennsylvania State University for assisting with LCA analysis of lexical measures
• Le Phan Quynh Dao for double-checking the questionnaire data
• the Vietnamese students (Thong, Thach, Linh, Oanh, Hang) who helped type the handwritten essays and checked them for accuracy
• Ms. Ho Thi Thuy Trang, who intercoded a part of the scripts for lexical errors
• the two anonymous reviewers for their valuable feedback, which has helped strengthen the report in numerous ways.

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Appendix A: Questionnaire survey

QUESTIONNAIRE

The current project explores Vietnamese IELTS learners’ perceptions of IELTS Writing Task 2 and their written Task 2 performance. We would like you to help us by answering the following questions about IELTS Task 2 writing, based on your own experience. Your answers will be used for research purpose only; hence, your personal information and answers will be kept confidential.

IELTS Writing Task 2 asks test-takers to write an essay that presents their ideas about certain topics. The candidates need to express their opinions and support them with some facts, evidence, and examples in an essay. The time recommended for this task is 45 minutes and the expected word length is 250 words.

Part 1: BACKGROUND INFORMATION

This section asks about your background information. Please write your answer in the space provided or tick (✔) the appropriate box.

1. Your name/ID*:

* You can use your real name, a pseudonym or a name code of your own choice, but please remember to use it consistently in the questionnaire and in the two IELTS writing tasks you wrote (if applicable).

If you have completed two IELTS Task 2 essays, you DO NOT need to answer the questions 2-11.

2. Your gender: Female / Male
3. Your age:
4. Your job:
5. Your major:
6. Have you studied abroad in English-speaking countries or where English is used as a means of instruction or communication? Yes / No. If yes, for how long?
7. Have you had any other overseas experience (travelling, exchange programs, camp, etc.)? Yes / No. If yes, for how long?
8. How long have you studied IELTS Writing Task 2 for?
9. Have you ever taken an IELTS before? Yes / No. If yes, what is your highest overall band of IELTS?
10. What do you think your IELTS Writing Task 2 score is now? About
11. Your target IELTS score: Academic module / General module

PART 2: MOTIVATIONS TO STUDY IELTS

I. This section asks about your reasons for studying IELTS. You can tick (✔) more than one answer.

• to apply for scholarships to study overseas.

• to meet language requirements for university graduation.

• to meet language requirements for postgraduate courses.

• to gain internationally-standardised qualifications.

• to improve my English language skills.

• to get a favourite job.

• to please my parents.

• to satisfy my personal interests.

• Others: .

II. This section asks about your motivation to study IELTS. For each of the following statements, tick (✔) the most appropriate answer (1-7).

1: Very untrue of me 2: Untrue of me 3: Somewhat untrue of me 4: Undecided 5: Somewhat true of me 6: True of me 7: Very true of me

Part 3.:IELTS LEARNERS’ PERCEPTIONS OF IELTS WRITING TASK 2

I. This section asks about the influence of task features on your IELTS Task 2 writing.

Tick (✔) the most appropriate answer (1-7).

1: Not at all

2: Not really

3: Very little

4: Undecided

5: To a certain extent

6: To a large extent

7: To a very large extent

II. This section asks about the difficulties you might have while writing IELTS Task 2.

For each of the following statements, tick (✔) the most appropriate answer (1-7).

1: Very untrue of me

2: Untrue of me

3: Somewhat untrue of me 4: Undecided

5: Somewhat true of me

6: True of me

7: Very true of me

III. This section asks about the influence of personal factors on your IELTS Task 2 writing. For each of the following statements, tick (✔) the most appropriate answer (1-7).

1: Very untrue of me 2: Untrue of me 3: Somewhat untrue of me 4: Undecided 5: Somewhat true of me 6: True of me 7: Very true of me

Part 4: IELTS LEARNERS’ PERCEIVED LEXICAL SELF-EFFICACY FOR IELTS WRITING TASK 2

This section asks about your ability to use lexical resource in IELTS Writing Task 2.

For each of the following statements, tick (✔) the most appropriate answer (1-7).

1: Very untrue of me

2: Untrue of me

3: Somewhat untrue of me

4: Undecided

5: Somewhat true of me

6: True of me

7: Very true of me

Thank you for your time and help!

Questionnaire Survey (Vietnamese version)

PHIẾU KHẢO SÁT

Đề tài này tìm hiểu ý kiến của các bạn là người học IELTS về bài viết IELTS số 2. Chúng tôi mong các bạn giúp trả lời những câu hỏi sau về bài viết IELTS số 2, dựa vào trải nghiệm của mình. Câu trả lời của các bạn sẽ chỉ được dùng cho mục đích nghiên cứu, và sẽ được giữ kín, cũng như thông tin cá nhân (tên thật của bạn v.v.) cũng sẽ không được tiết lộ dưới bất cứ hình thức nào.

Bài viết IELTS số 2 yêu cầu thí sinh viết một bài luận về một chủ đề cho sẵn. Bài luận có thể là bài trình bày quan điểm cá nhân, thảo luận hai mặt của vấn đề, thảo luận nguyên nhân-kết quả của một vấn đề, hay thảo luận và giải quyết vấn đề. Thí sinh được yêu cầu viết khoảng 250 từ trong khoảng 45 phút.

PHẦN 1: THÔNG TIN CÁ NHÂN

Phần này hỏi về thông tin cá nhân. Hãy viết câu trả lời vào chỗ trống hoặc chọn (✔) ô phù hợp.

1. Họ và tên/mã số*:

(*Bạn có thể dùng tên thật của mình, tên giả hay một mã số tuỳ chọn, nhưng xin bạn vui lòng dùng cùng tên/ mã số bạn đã dùng trong hai bài viết (nếu có).)

Nếu bạn đã viết hai bài luận, bạn KHÔNG cần trả lời các câu 2-11.

2. Giới tính: Nữ / Nam

3. Tuổi:

4. Nghề nghiệp:

5. Chuyên ngành/Chuyên môn:

6. Bạn đã bao giờ đi học ở các nước tiếng Anh là tiếng mẹ đẻ hay ở nước mà tiếng Anh được sử dụng để giảng dạy hoặc giao tiếp) chưa? Đã đi / Chưa đi. Nếu Đã đi, trong bao lâu?

7. Bạn đã từng ra nước ngoài chưa (du lịch, tham gia các chương trình trao đổi, tham gia trại hè, v.v.)? Đã đi / Chưa đi. Nếu Đã đi, trong bao lâu?

8. Bạn học bài viết IELTS số 2 được bao lâu rồi?

9. Trước đây bạn đã thi IELTS chưa? Đã thi / Chưa thi. Nếu Đã thi, kết quả IELTS cao nhất của bạn là bao nhiêu?

10. Bạn nghĩ hiện tại điểm bài viết IELTS số 2 của mình là bao nhiêu? Khoảng

11. Điểm IELTS mà bạn muốn đạt được là:

Bài thi Học thuật (Academic module) / Bài thi Tổng quát (General module)

PART 2. ĐỘNG LỰC LUYỆN THI IELTS

I. Phần này hỏi về lý do bạn luyện thi IELTS. Bạn có thể chọn (✔) hơn một câu trả lời.

Tôi luyện thi IELTS …

• để nộp đơn xin học bổng đi học ở nước ngoài.

• để đáp ứng yêu cầu ngoại ngữ khi tốt nghiệp đại học.

• để đáp ứng yêu cầu ngoại ngữ cho khoá đào tạo sau đại học.

• để đạt được chứng chỉ ngoại ngữ chuẩn quốc tế.

• để nâng cao kỹ năng tiếng Anh.

• để xin được việc làm yêu thích.

• để làm hài lòng bố mẹ.

• để thoả mãn sở thích cá nhân.

• Lý do khác: .

II. Phần này hỏi về động lực luyện thi IELTS của bạn. Đối với mỗi phát biểu dưới đây, hãy chọn

(✔) câu trả lời (1-7) phù hợp nhất với bạn.

1: Hoàn toàn không đúng 2: Không đúng 3: Phần nào không đúng 4: Không xác định 5: Phần nào đúng 6: Đúng 7: Hoàn toàn đúng

Phần 3: CẢM NHẬN CỦA NGƯỜI HỌC IELTS VỀ BÀI VIẾT SỐ 2

I. Phần này hỏi về mức độ ảnh hưởng của các yếu tố liên quan đến bài viết IELTS số 2 của bạn. Hãy chọn (✔) câu trả lời (1-7) phù hợp nhất với bạn.

1: Hoàn toàn không ảnh hưởng 2: Không ảnh hưởng 3: Phần nào không ảnh hưởng 4: Không xác định 5: Phần nào có ảnh hưởng 6: Ảnh hưởng nhiều 7: Ảnh hưởng rất nhiều

II. Phần này hỏi về những khó khăn bạn có thể gặp phải khi viết bài viết IELTS số 2. Đối với mỗi phát biểu dưới đây, hãy chọn (✔) câu trả lời (1-7) phù hợp nhất với bạn.

1: Hoàn toàn không đúng 2: Không đúng 3: Phần nào không đúng 4: Không xác định 5: Phần nào đúng 6: Đúng 7: Hoàn toàn đúng

III. Phần này hỏi về trải nghiệm viết bài viết IELTS số 2 của bạn. Đối với mỗi phát biểu dưới đây, hãy chọn (✔) câu trả lời (1-7) phù hợp nhất với bạn.

1: Hoàn toàn không đúng 2: Không đúng 3: Phần nào không đúng

4: Không xác định 5: Phần nào đúng 6: Đúng 7: Hoàn toàn đúng

Phần 4: VIỆC SỬ DỤNG TỪ VỰNG KHI VIẾT BÀI VIẾT IELTS SỐ 2

Phần này hỏi về việc sử dụng từ vựng của bạn khi viết bài viết IELTS số 2. Đối với mỗi phát biểu, hãy chọn (✔) câu trả lời (1-7) phù hợp nhất với bạn.

1: Hoàn toàn không đúng 2: Không đúng 3: Phần nào không đúng 4: Không xác định 5: Phần nào đúng 6: Đúng 7: Hoàn toàn đúng

Xin chân thành cảm ơn!

Appendix B: Information sheets and consent forms

INFORMATION SHEET (For teacher facilitators)

Project title: Vietnamese IELTS Learners’ Perceptions of IELTS Writing Task 2 and their IELTS Writing Task 2 Performance

The researchers

We are Dr Bao Trang Thi Nguyen, Dr Thi Thanh Binh Nguyen and Dr Quynh Nhu Phan, working as lecturers and researchers at the University of Foreign Languages, Hue University.

The research project

This research project is designed to explore Vietnamese IELTS learners’ perceptions of IELTS Writing Task 2, and their written Task 2 performance. As you might know, Vietnamese learners of IELTS are among the most popular IELTS learner groups in the world. However, not much is known about them in IELTS research. This study is therefore instrumental in informing IELTS writing pedagogy and marking for Vietnamese learners and learners in other similar contexts. It is funded by IDP IELTS Australia.

Your participation in the research project

You are invited to participate in this study since you are teaching an IELTS course for some time. No one else rather than you could help us approach your IELTS learners. You will facilitate the data collection for this research, including questionnaire administration and/or the two IELTS Writing Task 2 tests. Your willingness to undertake this facilitator role in our research will help us obtain the Writing Task 2 data for the particular purpose of our research, as said.

If you decide to participate, you will be asked to let us approach your IELTS learners to ask for their voluntary participation in the project. Your students will be invited to complete a questionnaire and/or write two IELTS Task 2 writing essays. The questionnaire aims to understand their IELTS’ learning motivation, their perceptions of IELTS Writing Task 2 difficulty and of the ways they use lexical resource in Writing Task 2 performance. It will be written in Vietnamese for its clarification and will take them about 15 minutes to complete. In appreciation for their time and effort, your learners will be paid 50,000 VND for completing the questionnaire. For your help to administer the questionnaire in one of your IELTS classes, you will be paid 100,000 VND.

Next, your learners will be invited to write two Task 2 essays of different topics on ready-made paper sheets in two successive weeks. If you are willing to help us with test administration, you will assign your learners two IELTS Task 2 essays, which we will provide, in two successive weeks in your normal IELTS class hours as progress tests. As a normal class test, students are not allowed to use any materials rather than the task rubrics. You are kindly requested not to provide any help during the test. For each essay, your learners will write at least 250 words, in a maximum of 50 minutes and will be paid 100,000 VND for each essay as appreciation tokens for their contribution. For your help to administer the Task 2 essays in one of your IELTS classes you will be paid 200,000 VND per task (test).

All the information your learners give in the questionnaire and/or their essays will be kept confidential. Their real names and the names of their institution/faculty/school/language center will not be identified in any way in the research or publications from this research. Access to the data will be restricted to the researchers and IDP IELTS Australia only.

Your participation in this project is entirely voluntary. You are not obliged to participate and if you decide not to participate, you can withdraw at any time you wish, without having to give a reason and without consequence.

If you have any query or concern or would like to be further informed about this research, please feel free to contact us at ntbtrang@hueuni.edu.vn, or nttbinh@hueuni.edu.vn, or pquynhnhu@ hueuni.edu.vn, or our IELTS research coordinator, Jenny Osborne, at jenny.osborne@idp.com.

Thank you very much for your cooperation in advance.

Dr Bao Trang Thi Nguyen

Dr Thi Thanh Binh Nguyen

Dr Quynh Nhu Phan

BẢNG THÔNG TIN (Dành cho giáo viên)

Đề tài nghiên cứu: Nhận thức của người học IELTS Việt Nam về bài viết IELTS số 2 và trải nghiệm viết bài viết số 2 của họ

Nghiên cứu viên

Chúng tôi là TS. Nguyễn Thị Bảo Trang, TS. Nguyễn Thị Thanh Bình và TS. Phan Quỳnh Như, giảng viên và nghiên cứu viên tại trường Đại trường Đại học Ngoại ngữ, Đại học Huế.

Nghiên cứu

Nghiên cứu này nhằm tìm hiểu nhận thức của người học IELTS Việt Nam về bài viết IELTS số 2, và trải nghiệm viết bài viết số 2 của họ. Như Thầy/Cô biết, người học IELTS Việt Nam là một trong những nhóm người học IELTS phổ biến nhất trên thế giới. Tuy nhiên, vẫn chưa có nhiều nghiên cứu về nhóm người học này. Vì vậy nghiên cứu này là cần thiết giúp cải tiến phương pháp dạy và đánh giá kỹ năng viết IELTS cho đối tượng người học Việt Nam và người học ở các bối cảnh tương tự. Nghiên cứu này được tài trợ bởi IELTS IDP Úc.

Sự tham gia của Thầy/Cô vào dự án

Thầy/Cô được mời tham gia vào dự án nghiên cứu này vì Thầy/Cô đang dạy IELTS một thời gian. Không ai khác ngoài Thầy/Cô có thể giúp các nhà nghiên cứu tiếp cận người học IELTS.Thầy/ Cô sẽ giúp phối việc thu thập dữ liệu cho nghiên cứu này, bao gồm phát và thu bảng hỏi, và/hoặc hướng dẫn họ viết HAI bài viết IELTS số 2. Việc Thầy/Cô sẵn lòng đảm nhận vai trò hướng dẫn này sẽ giúp chúng tôi thu thập được số liệu về bài viết số 2 đáp ứng mục tiêu cụ thể của dự án này, như đã trình bày ở trên.

Nếu Thầy/Cô đồng ý tham gia, Thầy/Cô sẽ được yêu cầu giúp chúng tôi tiếp cận người học IELTS của Thầy/Cô để đề nghị họ tình nguyện tham gia vào nghiên cứu này. Người học của Thầy/Cô sẽ được yêu cầu điền vào bảng hỏi và/hoặc viết HAI bài viết IELTS số 2. Bảng hỏi nhằm tìm hiểu về động lực của người học khi học IELTS, nhận thức của họ về độ khó của bài viết số 2 và sự tự tin của họ trong việc sử dụng từ vựng khi họ viết bài viết số 2. Bảng hỏi sẽ được viết bằng tiếng Việt để giúp họ hiểu vấn đề rõ ràng và họ sẽ mất khoảng 15 phút để hoàn thành bảng hỏi. Để cảm ơn thời gian và công sức của người học khi điền thông tin bảng hỏi, chúng tôi sẽ trả họ 50,000 VND. Chúng tôi xin gửi Thầy/Cô 100,000 VND để cảm ơn Thầy /Cô đã hỗ trợ lấy số liệu bảng hỏi ở mỗi lớp.

Tiếp theo, người học sẽ được mời viết HAI bài viết IELTS số 2 về các chủ đề khác nhau trên giấy cho sẵn vào hai tuần liên tiếp. Nếu Thầy/Cô đồng ý tham gia, Thầy/Cô sẽ giúp điều hành bằng cách cho người học viết HAI bài viết IELTS số 2 theo chủ đề chúng tôi cung cấp vào hai tuần liên tiếp trong giờ học IELTS bình thường của Thầy/Cô. Hai bài viết này được xem như bài kiểm tra tiến bộ và người học sẽ không được phép sử dụng tài liệu khác nào ngoài đề bài. Thầy/Cô vui lòng không hướng dẫn thêm trong quá trình họ làm bài viết. Với mỗi bài viết, người học sẽ viết khoảng 250 từ trong thời gian tối đa 50 phút. Người học sẽ được trả 100,000 VND cho mỗi bài viết như là sự cảm ơn đến đóng góp của họ vào nghiên cứu này. Cho mỗi bài kiểm tra ở mỗi lớp, chúng tôi xin gửi Thầy/Cô 200,000 VND để cảm ơn Thầy /Cô đã điều hành việc viết bài của người học.

Tất cả thông tin người học của Thầy/Cô cung cấp trong bảng hỏi và/hoặc bài viết sẽ được giữ bí mật. Tên thật của họ và nơi họ học sẽ không được nhận dạng dưới bất cứ hình thức nào trong nghiên cứu hay các ấn phẩm xuất bản từ nghiên cứu này. Chỉ có các nhà nghiên cứu và tổ chức IELTS IDP Úc mới có thể tiếp cận số liệu gốc của nghiên cứu này.

Sự tham gia của Thầy/Cô vào nghiên cứu này là hoàn toàn tự nguyện và nếu Thầy/Cô quyết định không tham gia, Thầy/Cô có thể rút khỏi nghiên cứu vào bất cứ lúc nào Thầy/Cô muốn mà không cần nêu lý do hay không chịu hậu quả nào.

Nếu Thầy/Cô có câu hỏi gì hay muốn được cung cấp thêm thông tin về nghiên cứu này, xin liên hệ với chúng tôi qua email ntbtrang@hueuni.edu.vn, hoặc nttbinh@hueuni.edu.vn, hoặc pquynhnhu@hueuni.edu.vn, hoặc điều phối viên nghiên cứu IELTS, Jenny Osborne, tại địa chỉ jenny.osborne@idp.com.

Xin chân thành cảm ơn sự hợp tác của Thầy/Cô.

TS. Nguyễn Thị Bảo Trang

TS. Nguyễn Thị Thanh Bình

TS. Phan Quỳnh Như

INFORMATION SHEET (For learners)

Project title: Vietnamese IELTS Learners’ Perceptions of IELTS Writing Task 2 and their Task 2 Performance

The researchers

We are Dr Bao Trang Thi Nguyen, Dr Thi Thanh Binh Nguyen and Dr Quynh Nhu Phan, working as lecturers and researchers at the University of Foreign Languages, Hue University.

The research project

This research project is designed to explore Vietnamese IELTS learners’ perceptions of IELTS Writing Task 2, and their written Task 2 performance. As you might know, Vietnamese learners of IELTS are among the most popular IELTS learner groups in the world. However, not much is known about them in IELTS research. This study is therefore instrumental in informing IELTS writing pedagogy and marking for Vietnamese learners and learners in other similar contexts. It is funded by IDP IELTS Australia.

Your participation in the research project

You are invited to participate in this study, since you are taking an IELTS course and have been learning IELTS for some time. No one else rather than you could provide us with usefu information for the particular purpose of our research, as said.

If you decide to participate, you will be asked to complete a questionnaire and/or write two IELTS Task 2 writing essays. The questionnaire aims to understand your IELTS’ learning motivation, your perceptions of the Writing Task 2 difficulty and your awareness of the lexical resource in Writing Task 2 performance. It will be written in Vietnamese for your clarification and will take you about 15 minutes to complete. In appreciation for your time and effort, you will be paid 50,000 VND for completing the questionnaire.

Next, you will be invited to write two IELTS Writing Task 2 essays of different topics on readymade paper sheets in two successive weeks. If you are willing to participate, for each essay, you will write at least 250 words, in a maximum of 50 minutes in your normal IELTS class hours as a progress test and will be paid 100,000 VND for each essay as appreciation tokens for your contribution.

All the information you give in the questionnaire and/or your essays will be kept confidential. Your real names and the names of your institution/faculty/school/language center will not be identified in any way in the research or publications from this research. Access to the data will be restricted to the researchers and IDP IELTS Australia only.

Your participation in this project is entirely voluntary. You are not obliged to participate and if you decide not to participate, you can withdraw at any time you wish, without having to give a reason and without consequence.

If you have any query or concern or would like to be further informed about this research, please feel free to contact us at ntbtrang@hueuni.edu.vn, or nttbinh@hueuni.edu.vn, or pquynhnhu@ hueuni.edu.vn, or our IELTS research coordinator, Jenny Osborne, at jenny.osborne@idp.com.

Thank you very much for your cooperation in advance.

Dr Bao Trang Thi Nguyen

Dr Thi Thanh Binh Nguyen

Dr Quynh Nhu Phan

BẢNG THÔNG TIN (Dành cho người học)

Đề tài nghiên cứu: Nhận thức của người học IELTS Việt Nam về bài viết IELTS số 2 và trải nghiệm viết bài viết số 2 của họ

Nghiên cứu viên

Chúng tôi là TS. Nguyễn Thị Bảo Trang, TS. Nguyễn Thị Thanh Bình và TS. Phan Quỳnh Như, giảng viên và nghiên cứu viên tại trường Đại trường Đại học Ngoại ngữ, Đại học Huế.

Nghiên cứu

Nghiên cứu này nhằm tìm hiểu nhận thức của người học IELTS Việt Nam về bài viết IELTS số 2, và trải nghiệm bài viết IELTS số 2 của họ. Như bạn biết, người học IELTS Việt Nam là một trong những nhóm người học IELTS phổ biến nhất trên thế giới. Tuy nhiên, vẫn chưa có nhiều nghiên cứu về nhóm người học này. Vì vậy nghiên cứu này là cần thiết giúp cải tiến phương pháp dạy và đánh giá kỹ năng viết IELTS cho đối tượng người học Việt Nam và người học ở các bối cảnh tương tự. Nghiên cứu này được tài trợ bởi IELTS IDP Úc.

Sự tham gia của bạn vào nghiên cứu

Bạn được mời tham gia vào nghiên cứu này vì bạn đang theo học khoá IELTS và bạn đã học IELTS một thời gian. Không ai khác ngoài bạn có thể cung cấp cho chúng tôi những thông tin hữu ích đáp ứng mục tiêu cụ thể của nghiên cứu này, như đã trình bày ở trên.

Nếu bạn đồng ý tham gia, bạn sẽ được yêu cầu điền vào bảng hỏi và/hoặc viết HAI bài viết IELTS số 2. Bảng hỏi nhằm tìm hiểu về động lực của bạn khi học IELTS, nhận thức của bạn về độ khó của bài viết IELTS số 2 và việc sử dụng từ vựng khi bạn viết bài viết IELTS số 2. Bảng hỏi sẽ được viết bằng tiếng Việt để giúp bạn hiểu vấn đề rõ ràng và bạn sẽ mất khoảng 15 phút để hoàn thành bảng hỏi. Để cảm ơn thời gian và công sức của bạn khi điền thông tin bảng hỏi, chúng tôi sẽ trả bạn 50,000 VND.

Tiếp theo, bạn sẽ được mời viết HAI bài viết về các chủ đề khác nhau trên giấy cho sẵn vào hai tuần khác nhau. Nếu bạn đồng ý tham gia, với mỗi bài viết, bạn sẽ viết khoảng 250 từ trong thời gian tối đa 50 phút ở lớp học IELTS của bạn, và bài viết này được xem như một bài kiểm tra tiến bộ. Bạn sẽ được trả 100,000 VND cho mỗi bài viết như là sự cảm ơn đến đóng góp của bạn vào nghiên cứu này.

Tất cả thông tin bạn cung cấp trong bảng hỏi và/hoặc bài viết sẽ được giữ bí mật. Tên thật của bạn và tên của nơi bạn học sẽ không được nhận dạng dưới bất cứ hình thức nào trong nghiên cứu hay các ấn phẩm xuất bản từ nghiên cứu này. Chỉ có các nghiên cứu viên và tổ chức IELTS IDP Úc mới có thể tiếp cận số liệu gốc của nghiên cứu này.

Sự tham gia của bạn vào nghiên cứu này là hoàn toàn tự nguyện và nếu bạn quyết định không tham gia, bạn có thể rút khỏi nghiên cứu vào bất cứ lúc nào bạn muốn mà không cần nêu lý do hay không chịu hậu quả nào.

Nếu bạn có câu hỏi gì hay muốn được cung cấp thêm thông tin về nghiên cứu này, xin liên hệ với chúng tôi qua email ntbtrang@hueuni.edu.vn, hoặc nttbinh@hueuni.edu.vn, hoặc pquynhnhu@ hueuni.edu.vn, hoặc điều phối viên nghiên cứu IELTS, Jenny Osborne, tại địa chỉ jenny.osborne@ idp.com.

Xin chân thành cảm ơn sự hợp tác của bạn.

TS. Nguyễn Thị Bảo Trang

TS. Nguyễn Thị Thanh Bình

TS. Phan Quỳnh Như

CONSENT FORM (For teacher facilitators)

I, , agree to participate in the research project Vietnamese IELTS Learners’ Perceptions of IELTS Writing Task 2 and their IELTS Writing Task 2 Performance being funded by IDP IELTS Australia and conducted by Dr Bao Trang Thi Nguyen, Dr Thi Thanh Binh Nguyen and Dr Quynh Nhu Phan - lecturers and researchers at the University of Foreign Languages, Hue University.

I understand that the purpose of this study is to explore Vietnamese IELTS learners’ perceptions of IELTS Writing Task 2, and their written Task 2 performance in order to inform IELTS writing pedagogy and marking for Vietnamese learners and learners in other similar contexts.

I understand that I have been asked to participate in this research because I am teaching an IELTS course for some time. No one else rather than me could help the researchers approach my IELTS learners and facilitate the data collection for this research, including questionnaire administration and/or the two IELTS Writing Task 2 tests. I understand that my participation in this research will involve me (1) administering their completion of the questionnaire, and/or (2) supervising them to write two Task 2 essays in two successive weeks.

I understand that I will be asked to administer the learners’ completion of a questionnaire about their IELTS’ learning motivation, their perceptions of IELTS Writing Task 2 difficulty and of the ways they use lexical resource in IELTS Writing Task 2 performance. The questionnaire will be written in Vietnamese for its clarification, and will take them about 15 minutes to complete.

I understand that I will be asked to supervise the learners to write TWO IELTS Task 2 essays of two topics on ready-made paper sheets in two successive weeks in my normal IELTS class hours as a progress test. As a normal class test, the learners are not allowed to use any materials rather than the test rubrics, and I will not help them in any form during the test. For each essay, my learners will write at least 250 words, in a maximum of 50 minutes.

All the information my learners give in the questionnaire and/or their essays will be kept confidential, and their real name and the name of their institution/faculty/school/language center will not be used or identified in any way in the research or publications from this research.

I understand that the research data gathered from this project may be published in a form that does not identify me/my learners in any way and that access to the data will be restricted to the researchers and IDP IELTS Australia only.

I understand that I am not obliged to participate and if I decide not to participate, I can withdraw at any time I wish, without having to give a reason and without consequence.

I am aware that I can contact the researchers Dr Bao Trang Thi Nguyen, Dr Thi Thanh Binh Nguyen and Dr Quynh Nhu Phan on ntbtrang@hueuni.edu.vn, nttbinh@hueuni.edu.vn, and pquynhnhu@hueuni.edu.vn, or their IELTS research coordinator, Jenny Osborne, at jenny. osborne@idp.com for any further query or concern about this research.

I agree that Dr Bao Trang Thi Nguyen, Dr Thi Thanh Binh Nguyen and Dr Quynh Nhu Phan have answered all my questions fully and clearly.

Full name (participant)

Signature (participant)

Signature (researcher or delegate)

PHIẾU ĐỒNG Ý (Dành cho Giáo viên)

Tôi, , đồng ý tham gia vào nghiên cứu Nhận thức của người học IELTS Việt Nam về bài viết IELTS số 2 và trải nghiệm viết bài viết số 2 của họ được tài trợ bởi Tổ chức IELTS IDP Úc và thực hiện bởi TS. Nguyễn Thị Bảo Trang, TS. Nguyễn Thị Thanh Bình và TS. Phan Quỳnh Như, là giảng viên và nghiên cứu viên tại trường Đại trường Đại học Ngoại ngữ, Đại học Huế.

Tôi hiểu rằng mục tiêu của nghiên cứu này là tìm hiểu nhận thức của người học IELTS Việt Nam về bài viết IELTS số 2, và trải nghiệm viết bài của họ nhằm giúp cải tiến phương pháp dạy và đánh giá kỹ năng viết cho đối tượng người học Việt Nam và người học ở các ngữ cảnh tương tự.

Tôi hiểu rằng tôi được mời tham gia dự án này vì tôi đang dạy IELTS một thời gian. Không ai khác ngoài tôi có thể giúp các nhà nghiên cứu tiếp cận người học IELTS tôi đang dạy, và giúp các nghiên cứu viên điều phối việc thu thập số dữ liệu cho nghiên cứu này, bao gồm phát và thu bảng hỏi, và hướng dẫn họ viết HAI bài viết IELTS số 2. Tôi hiểu rằng việc tham gia của tôi vào dự án sẽ bao gồm (1) điều hành người học điền vào bảng hỏi và / hoặc (2) hướng dẫn người học viết HAI bài viết IELTS số 2 vào hai tuần khác nhau.

Tôi hiểu rằng tôi được yêu cầu điều hành người học điền bảng hỏi về động lực họ học IELTS, nhận thức của họ về độ khó của bài viết IELTS số 2 và việc sử dụng từ vựng khi họ viết bài viết IELTS số 2. Bảng hỏi sẽ được viết bằng tiếng Việt để giúp người học hiểu rõ vấn đề và họ sẽ mất khoảng 15 phút để hoàn thành bảng hỏi.

Tôi hiểu rằng tôi sẽ được yêu cầu hướng dẫn người học viết HAI bài viết IELTS số 2 về chủ đề khác nhau trên giấy in sẵn vào hai tuần liên tiếp ở các buổi học IELTS bình thường của tôi. Người học sẽ không được phép sử dụng tài liệu và tôi cũng sẽ không hướng dẫn gì thêm cho người học trong quá trình họ làm bài viết. Với mỗi bài viết, người học sẽ viết khoảng 250 từ trong thời gian tối đa 50 phút ở lớp học IELTS bình thường của tôi và bài viết này được xem như một bài kiểm tra tiến bộ.

Tất cả thông tin người học của tôi cung cấp trong bảng hỏi và bài viết sẽ được giữ bí mật. Tên thật của họ và tên của nơi họ học sẽ không được nhận dạng dù bất kỳ hình thức nào trong nghiên cứu hay các ấn phẩm xuất bản từ nghiên cứu này.

Tôi hiểu rằng số liệu nghiên cứu được thu thập từ nghiên cứu này có thể được xuất bản dưới hình thức mà thông tin cá nhân của tôi/của người học của tôi không được tiết lộ và chỉ có các nghiên cứu viên và tổ chức IELTS IDP Úc mới có thể tiếp cận số liệu của nghiên cứu này.

Tôi hiểu rằng sự tham gia của tôi vào nghiên cứu này là hoàn toàn tự nguyện và nếu tôi quyết định không tham gia, tôi có thể rút khỏi nghiên cứu vào bất cứ lúc nào tôi muốn mà không cần nêu lý do hay không chịu hậu quả nào.

Tôi ý thức rằng tôi có thể liên hệ với các nghiên cứu viên qua email ntbtrang@hueuni.edu.vn, hoặc nttbinh@hueuni.edu.vn, hoặc pquynhnhu@hueuni.edu.vn, hoặc điều phối viên nghiên cứu IELTS, Jenny Osborne, tại địa chỉ jenny.osborne@idp.com nếu tôi có câu hỏi gì thêm về đề tài nghiên cứu.

Tôi đồng ý rằng TS. Nguyễn Thị Bảo Trang, TS. Nguyễn Thị Thanh Bình và TS. Phan Quỳnh Như đã trả lời đầy đủ và rõ ràng các câu hỏi của tôi.

Họ & tên (người tham gia)

Chữ ký (người tham gia)

Chữ ký (nghiên cứu viên hoặc người đại diện)

CONSENT FORM (For learners)

I, , agree to participate in the research project Vietnamese IELTS Learners’ Perceptions of IELTS Writing Task 2 and their IELTS Writing Task 2 Performance being funded by IDP IELTS Australia and conducted by Dr Bao Trang Thi Nguyen, Dr Thi Thanh Binh Nguyen and Dr Quynh Nhu Phan - lecturers and researchers at the University of Foreign Languages, Hue University.

I understand that the purpose of this study is to explore Vietnamese IELTS learners’ perceptions of IELTS Writing Task 2, and their written Task 2 performance in order to inform IELTS writing pedagogy and marking for Vietnamese learners and learners in other similar contexts.

I understand that I have been asked to participate in this research because I am taking an IELTS course and have been learning IELTS for some time. No one else rather than me can give the researchers the information they need for the particular purpose of their research. I understand that my participation in this research will involve me (1) completing a questionnaire, and /or (2) writing two Task 2 essays in two successive weeks.

I understand that I will be asked to complete a questionnaire about my IELTS’ learning motivation, my perceptions of the Writing Task 2 difficulty and my awareness of the lexical resource in Writing Task 2 performance. The questionnaire will be written in Vietnamese, and it will take me about 15 minutes to complete.

I understand that I will be asked to write TWO IELTS Writing Task 2 essays of different topics on ready-made paper sheets in two successive weeks. Each essay I will write at least 250 words, in a maximum of 50 minutes in my normal IELTS class hours as a progress test.

All the information I give in the questionnaire and/or my essays will be kept confidential, and my real name and the name of my institution/faculty/school/language center will not be used or identified in any way in the research or publications from this research.

I understand that the research data gathered from this project may be published in a form that does not identify me in any way and that access to the data will be restricted to the researchers and IDP IELTS Australia only.

I understand that I am not obliged to participate and if I decide not to participate, I can withdraw at any time I wish, without having to give a reason and without consequence.

I am aware that I can contact the researchers Dr Bao Trang Thi Nguyen, Dr Thi Thanh Binh Nguyen and Dr Quynh Nhu Phan on ntbtrang@hueuni.edu.vn, nttbinh@hueuni.edu.vn, and pquynhnhu@hueuni.edu.vn, or their IELTS research coordinator, Jenny Osborne, at jenny. osborne@idp.com for any further query or concern about this research.

I agree that Dr Bao Trang Thi Nguyen, Dr Thi Thanh Binh Nguyen and Dr Quynh Nhu Phan have answered all my questions fully and clearly.

Full name (participant)

Signature (participant)

Signature (researcher or delegate)

PHIẾU ĐỒNG Ý (Dành cho người học)

Tôi, , đồng ý tham gia vào nghiên cứu Nhận thức của người học IELTS Việt Nam về bài viết IELTS số 2 và trải nghiệm viết bài viết số 2 của họ được tài trợ bởi Tổ chức IELTS IDP Úc và thực hiện bởi TS. Nguyễn Thị Bảo Trang, TS. Nguyễn Thị Thanh Bình và TS. Phan Quỳnh Như, là giảng viên và nghiên cứu viên tại trường Đại trường Đại học Ngoại ngữ, Đại học Huế.

Tôi hiểu rằng mục tiêu của nghiên cứu này là tìm hiểu nhận thức của người học IELTS Việt Nam về bài viết IELTS số 2, và trải nghiệm viết bài viết IELTS số 2 của họ nhằm giúp cải tiến phương pháp dạy và đánh giá kỹ năng viết cho đối tượng người học Việt Nam và người học ở các ngữ cảnh tương tự.

Tôi hiểu rằng tôi được mời tham gia dự án này vì tôi đang theo học khoá IELTS và tôi đã học IELTS một thời gian. Không ai khác ngoài tôi có thể cung cấp cho các nghiên cứu viên những thông tin hữu ích đáp ứng mục tiêu cụ thể của dự án này. Tôi hiểu rằng việc tham gia của tôi vào dự án sẽ bao gồm (1) điền vào bảng hỏi và / hoặc (2) viết HAI bài viết IELTS số 2 vào hai tuần liên tiếp.

Tôi hiểu rằng tôi được yêu cầu điền bảng hỏi về động lực tôi học IELTS, nhận thức của tôi về độ khó của bài viết IELTS số 2 và việc sử dụng từ vựng khi tôi viết bài viết IELTS số 2. Bảng hỏi sẽ được viết bằng tiếng Việt để giúp tôi hiểu rõ vấn đề và tôi sẽ mất khoảng 15 phút để hoàn thành bảng hỏi.

Tôi hiểu rằng tôi sẽ được yêu cầu viết HAI bài viết về hai chủ đề khác nhau trên giấy in sẵn vào hai tuần liên tiếp. Với mỗi bài viết, tôi sẽ viết khoảng 250 từ trong thời gian tối đa 50 phút ở lớp học IELTS bình thường của tôi và bài viết này được xem như một bài kiểm tra tiến bộ.

Tất cả thông tin tôi cung cấp trong bảng hỏi và bài viết sẽ được giữ bí mật. Tên thật của tôi và tên của nơi tôi học sẽ không được nhận dạng dưới bất cứ hình thức nào trong nghiên cứu hay các ấn phẩm xuất bản từ nghiên cứu này.

Tôi hiểu rằng số liệu nghiên cứu được thu thập từ nghiên cứu này có thể được xuất bản dưới hình thức mà thông tin cá nhân của tôi không được tiết lộ và chỉ có các nhà nghiên cứu và tổ chức IELTS IDP Úc mới có thể tiếp cận số liệu gốc của nghiên cứu này.

Tôi hiểu rằng sự tham gia của tôi vào nghiên cứu này là hoàn toàn tự nguyện và nếu tôi quyết định không tham gia, tôi có thể rút khỏi nghiên cứu vào bất cứ lúc nào tôi muốn mà không cần nêu lý do hay không chịu hậu quả nào.

Tôi ý thức rằng tôi có thể liên hệ với các nhà nghiên cứu qua email ntbtrang@hueuni.edu.vn, hoặc nttbinh@hueuni.edu.vn, hoặc pquynhnhu@hueuni.edu.vn, hoặc điều phối viên nghiên cứu IELTS, Jenny Osborne, tại địa chỉ jenny.osborne@idp.com nếu tôi có câu hỏi gì thêm về nghiên cứu này.

Tôi đồng ý rằng TS. Nguyễn Thị Bảo Trang, TS. Nguyễn Thị Thanh Bình và TS. Phan Quỳnh Như đã trả lời đầy đủ và rõ ràng các câu hỏi của tôi.

Họ & tên (người tham gia)

Chữ ký (người tham gia)

Chữ ký (nghiên cứu viên hoặc người đại diện)

Appendix C: IELTS Writing Task 2 essays and exit questionnaire

ESSAY 1

You should spend no more than 50 minutes on this task.

Write about the following topic:

Living in a country where you have to speak a foreign language can cause serious social problems, as well as practical problems.

To what extent do you agree or disagree with this statement?

Give reasons for your answer and include any relevant examples from your own knowledge or experience. Write at least 250 words.

Write here.

Exit questionnaire

Your name/ID*:

1. Your gender: female / male

2. Your age:

3. Your job:

4. Your major:

5. Have you ever studied abroad in English-speaking countries or where English is used as a means of communication? Yes / No

If yes, for how long?

6. Have you ever had any other overseas experience (travelling, exchange programs, camp, etc.)?

Yes / No. If yes, for how long?

7. How long have you studied IELTS Writing Task 2 for?

8. Have you taken an IELTS test before? Yes / No. If yes, what is your highest overall band of IELTS?

9. What do you think is your IELTS writing Task 2 score now? About

10. Your target IELTS score: Academic module / General module

11. Your reasons for studying IELTS:

12. How difficult is this IELTS writing task for you? Tick the corresponding number (1-7).

1 Very difficult 2 Difficult 3 Quite difficult 4 No idea 5 Quite easy

6 Easy 7 Very easy

Why?

*You can use your real name, a pseudonym or a name code of your own choice, but remember to use it consistently in the two IELTS writing tasks you write and in the questionnaire (if you are willing to participate). In case you use your real name, it will not be identified in anyway in this research.

Thank you for your participation in this research.

Exit Questionnaire - Vietnamese version

Khảo sát sau khi viết bài

Tên /Mã số của bạn*:

1. Giới tính:

Nữ

Nam

2. Tuổi:

3. Nghề nghiệp:

4. Chuyên ngành/Chuyên môn:

5. Bạn đã bao giờ đi học ở các nước tiếng Anh là tiếng mẹ đẻ hay ở nước mà tiếng Anh được sử dụng để giảng dạy hoặc giao tiếp chưa? Đã đi / Chưa đi. Nếu Đã đi, trong bao lâu?

6. Bạn đã từng ra nước ngoài chưa (du lịch, tham gia các chương trình trao đổi, tham gia trại hè, v.v.)? Đã đi / Chưa đi. Nếu Đã đi, trong bao lâu?

7. Bạn đã học viết bài IELTS số 2 bao lâu rồi?

8. Trước đây bạn đã thi IELTS chưa? Đã thi / Chưa thi. Nếu Đã thi, kết quả IELTS cao nhất của bạn là bao nhiêu?

9. Bạn nghĩ hiện tại điểm bài Viết IELTS số 2 của mình là bao nhiêu? Khoảng

10. Điểm IELTS mà bạn muốn đạt được là: Bài thi Học thuật (Academic module) / Bài thi Tổng quát (General module)

11. Lý do bạn học IELTS là:

12. Theo bạn, bài viết mà bạn vừa hoàn thành dễ hay khó? Hãy chọn số phù hợp (1-7). 1 Rất khó 2 Khó 3 Khá khó 4 Không có ý kiến 5 Khá dễ 6 Dễ 7 Rất dễ

Tại sao?

Bạn có thể dùng tên thật của mình hoặc tên giả hay một mã số tuỳ chọn, nhưng xin bạn vui lòng dùng cùng tên/ mã số này cho bài viết tiếp theo và bảng hỏi (nếu bạn sẵn lòng tham gia). Trong trường hợp bạn dùng tên thật, tên của bạn sẽ không bị nhận dạng dưới bất cứ hình thức nào trong nghiên cứu này.

Xin chân thành cảm ơn!

ESSAY 2

You should spend no more than 50 minutes on this task.

Write about the following topic:

Some people believe that unpaid community service should be a compulsory part of high school programs (for example, working for a charity, improving the neighbourhood or teaching sports to younger children).

To what extent do you agree or disagree with this statement?

Give reasons for your answer and include any relevant examples from your own knowledge or experience. Write at least 250 words.

Write here.

Exit questionnaire

Your name/ID*:

1. Have you written an IELTS Writing Task 2 essay in this research?

Yes / No

If yes, just answer Question 13.

2. Your gender: female / male

3. Your age:

4. Your job:

5. Your major:

6. Have you ever studied abroad in English-speaking countries or where English is used as a means of communication? Yes / No

If yes, for how long?

7. Have you ever had any other overseas experience (travelling, exchange programs, camp, etc.)?

Yes / No. If yes, for how long?

8. How long have you studied IELTS Writing Task 2 for?

9. Have you taken an IELTS test before? Yes / No. If yes, what is your highest overall band of IELTS?

10. What do you think is your IELTS writing Task 2 score now? About

11. Your target IELTS score: Academic module / General module

12. Your reasons for studying IELTS:

13. How difficult is this IELTS writing task for you? Tick the corresponding number (1-7).

1 Very difficult 2 Difficult 3 Quite difficult 4 No idea 5 Quite easy 6 Easy 7 Very easy

Why?

*You can use your real name, a pseudonym or a name code of your own choice, but remember to use it consistently in the two IELTS writing essay you write and in the questionnaire (if you are willing to participate). In case you use your real name, it will not be identified in anyway in this research.

Thank you for your participation in this research.

Exit Questionnaire - Vietnamese version

Khảo sát sau khi viết bài

Tên /Mã số của bạn*:

1. Bạn đã tham gia viết bài viết IELTS số 2 lần thứ nhất trong nghiên cứu này không? Có / Không Nếu Có, vui lòng chỉ trả lời câu hỏi số 13.
2. Giới tính: Nữ / Nam
3. Tuổi:
4. Nghề nghiệp:
5. Chuyên ngành/Chuyên môn:
6. Bạn đã bao giờ đi học ở các nước tiếng Anh là tiếng mẹ đẻ hay ở nước mà tiếng Anh được sử dụng để giảng dạy hoặc giao tiếp chưa? Đã đi / Chưa đi. Nếu Đã đi, trong bao lâu?
7. Bạn đã từng ra nước ngoài chưa (du lịch, tham gia các chương trình trao đổi, tham gia trại hè, v.v.)? Đã đi / Chưa đi. Nếu Đã đi, trong bao lâu?
8. Bạn đã học viết bài IELTS số 2 bao lâu rồi?
9. Trước đây bạn đã thi IELTS chưa? Đã thi / Chưa thi. Nếu Đã thi, kết quả IELTS cao nhất của bạn là bao nhiêu?
10. Bạn nghĩ hiện tại điểm bài Viết IELTS số 2 của mình là bao nhiêu? Khoảng
11. Điểm IELTS mà bạn muốn đạt được là: Bài thi Học thuật (Academic module) / Bài thi Tổng quát (General module)
12. Lý do bạn học IELTS là:
13. Theo bạn, bài viết mà bạn vừa hoàn thành dễ hay khó? Hãy chọn số phù hợp (1-7).

1 Rất khó 2 Khó 3 Khá khó 4 Không có ý kiến 5 Khá dễ 6 Dễ 7 Rất dễ

Tại sao?

*Bạn có thể dùng tên thật của mình hoặc tên giả hay một mã số tuỳ chọn, nhưng xin bạn vui lòng dùng cùng tên/ mã số này cho bài viết tiếp theo và bảng hỏi (nếu bạn sẵn lòng tham gia). Trong trường hợp bạn dùng tên thật, tên của bạn sẽ không bị nhận dạng dưới bất cứ hình thức nào trong nghiên cứu này.

Xin chân thành cảm ơn!

Appendix D: The taxonomy for coding lexical errors in the written scripts

Author biodata

Bao Trang Thi Nguyen

Bao Trang Thi Nguyen is a lecturer at the Faculty of English, University of Foreign Languages, Hue University, Vietnam. She teaches various subjects in Applied Linguistics for undergraduate and postgraduate students. She received an MA in Applied Linguistics from the University of Queensland, Australia and a PhD in the same area from Victoria University of Wellington, New Zealand. Bao Trang researches in the field of task-based language teaching and learning (TBLT), with a particular focus on task design, learner proficiency and oral and written language production, and assessment. She has several book chapters published by John Benjamins, Bloombury, Springer and Routledge. Her research work has also appeared in a number of journals such as TESOL Journal, Language Teaching Research, Asia Pacific Journal of Education, International Journal of Comparative Education and Development, Language Teaching for Young Learners, and Language Related Research.

Thi Thanh Binh Nguyen

Thi Thanh Binh Nguyen is a lecturer at the Faculty of International Studies, University of Foreign Languages, Hue University, Vietnam. She teaches English language skills for undergraduates majoring in English and International Studies. Thi Thanh Binh received her MA in English Language Teaching from University of Foreign Languages, Hue University and her EdD in Education from the University of Technology, Sydney, Australia. Her research interests are critical thinking in ELT, culture teaching and learning, and IELTS pedagogy.

Quynh Nhu Phan

Quynh Nhu Phan is a lecturer at University of Foreign Languages, Hue University. She teaches various subjects in Applied Linguistics for undergraduate and postgraduate students. She obtained her MA in Applied Linguistics from the University of Queensland, Australia and her PhD in Education from the University of Technology, Sydney, Australia. Her ongoing research interests have been in the areas of teaching English as a foreign language, teacher education, and teacher professional learning. Her research has been presented at international conferences such as AILA, JALT, VIETESOL and SEAMEO, and published in such national journals as Journal of Science, Hue University Journal of Science and Journal of Language and Life.