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Article
Psychometric Evaluation of Lexical Diversity Indices: Assessing Length Effects
Journal of Speech, Language, and Hearing Science
  • Gerasimos Fergadiotis, Portland State University
  • Heather Harris Wright, East Carolina University
  • Samuel B. Green, Arizona State University
Document Type
Post-Print
Publication Date
1-1-2015
Subjects
  • Lexical phonology,
  • Linguistics -- Research -- United States,
  • Aphasia -- Case studies
Abstract
Purpose—Several novel techniques have been developed recently to assess the breadth of speaker’s vocabulary exhibited in a language sample. The specific aim of this study was to increase our understanding of the validity of the scores generated by different lexical diversity (LD) estimation techniques. Four techniques were explored: D, Maas, Measure of Textual Lexical Diversity (MTLD), and the Moving Average Type Token Ratio (MATTR). Method—Four LD indices were estimated for language samples on four discourse tasks (procedures, eventcasts, story retell, and recounts) from 442 neurologically intact adults. The resulting data were analyzed using structural equation modeling. Results—The scores on the MATTR and MTLD estimation techniques were stronger indicators of the LD of the language samples. The results for the other two techniques were consistent with the presence of method factors representing construct-irrelevant sources. Conclusions—These findings offer a deeper understanding of the relative validity of the four estimation techniques and should assist clinicians and researchers in the selection of LD measures of language samples that minimize construct-irrelevant sources.
Description

This is the author's version of an article which was subsequently published in the Journal of Speech, Language, and Hearing Research (2015): 1-13. Copyright (2015) American Speech-Language-Hearing Association.

http://jslhr.pubs.asha.org/

Persistent Identifier
http://archives.pdx.edu/ds/psu/16463
Citation Information
Fergadiotis, G., Wright, H. H., & Green, S. B. (2015). Psychometric Evaluation of Lexical Diversity Indices: Assessing Length Effects. Journal of Speech, Language, and Hearing Research, 1-13.