Short texts, best-fitting curves and new measures of lexical diversity

Abstract

Following up on recent work by Malvern and Richards (1997, this issue; McKee et al., 2000) concerning the measurement of lexical diversity through curve fitting, the present study compares the accuracy of five formulae in terms of their ability to model the type-token curves of written texts produced by learners and native speakers. The most accurate models are then used to consider unresolved issues that have been at the forefront of past research on lexical diversity: the relationship between lexical diversity and age, second language (L2) instruction, L2 proficiency, first language (L1) background, writing quality and vocabulary knowledge. The participants in the study comprise 140 Finnish-speaking and 70 Swedish-speakinglearners of English, and an additional group of 66 native English speakers. The data include written narrative descriptions of a silent film, and the results show that two of the curve-fitting formulae provide accurate models of the type-token curves of over 90% of the texts. The texts for which accurate models were obtained were subjected to further analyses, and the results indicate a clear relationship between lexical diversity and amount of instruction, but a more complicated relationship between lexical diversity and L1 background, writing quality and vocabulary knowledge.

Analysing lexical richness in French learner language: what frequency lists and teacher judgements can tell us about basic and advanced words

“…We compare different operationalisations of the AG with a well-known measure of lexical diversity, D (Malvern et al, 2004), which represents the single parameter of a mathematical function that models the falling TTR curve (see also Jarvis, 2002 andMcCarthy andJarvis, 2007 for an appraisal of this measure). The different measures can give us an indication to what extent the students from the three groups differ from each other in the quantity and/or in the quality of the vocabulary they use.…”

The variance of lexical diversity profiles and its relationship to learning style

“…There is not a linear relationship between greater rarity or diversity and quality. This may help us to understand why L2 learners who are classified into groups according to the amount of L2 instruction produce lexical diversity profiles which are highly heterogeneous (Jarvis, 2002). Above a certain level of lexical diver sity, Jarvis found a negative correlation between D and holistic quality ratings of the texts.…”

“…Two of the main paths to assess vocabulary richness have been to assess the proportions of rare lexis in learner output (Laufer and Nation 1995) or the variety of lexis used (Malvern, Richards, Chipere and Durán 2004). Whilst at higher proficiency levels learners tend to use rarer lexis, there is not always a linear relationship between actual or presumed higher levels of proficiency and lexical diversity (Jarvis 2002). In other words, there tends to be considerable heterogeneity from scores in learners' lexical diversity when higher language proficiency learners are tested (Read 2005).…”

Teasing out the role of age and exposure in EFL learners’ lexical profiles: A comparison of children and adults

“…Studies that address measures of lexical richness (e. g. lexical variation, lexical frequency) typically focus on relating these to writing quality and proficiency levels (e. g. Laufer and Nation 1995;Jarvis 2002;Malvern and Richards 2002;Zareva et al 2005). Few studies have compared lexical richness in learners of different age with similar proficiency levels.…”