Measuring Children’s Lexical Diversity: Differentiating Typical and Impaired Language Learners This study evaluated the extent to which measures of lexical diversity (type-token ratio and number of different words produced) differentiated children with specific language impairment (SLI) from children whose language skills were following typical developmental expectations. Analysis of 50- and 100-utterance samples revealed that children with SLI did not significantly ... Research Article
Research Article  |   December 01, 1995
Measuring Children’s Lexical Diversity: Differentiating Typical and Impaired Language Learners
 
Author Affiliations & Notes
  • Ruth V. Watkins
    Department of Speech and Hearing Science, University of Illinois at Urbana-Champaign
  • Donna J. Kelly
    Department of Speech Pathology and Audiology, Marquette University, Milwaukee, WI
  • Heidi M. Harbers
    Department of Speech and Communication Studies, Edinboro University of Pennsylvania, Edinboro
  • Wendy Hollis
    Department of Speech and Hearing Science, University of Illinois at Urbana-Champaign
  • Contact author: Ruth Watkins, PhD, University of Illinois, Speech and Hearing Science, 901 S. Sixth St., Champaign, IL 61820. E-mail: rwatkins@ux1.cso.uiuc.edu
Article Information
Language Disorders / Specific Language Impairment / Language / Research Articles
Research Article   |   December 01, 1995
Measuring Children’s Lexical Diversity: Differentiating Typical and Impaired Language Learners
Journal of Speech, Language, and Hearing Research, December 1995, Vol. 38, 1349-1355. doi:10.1044/jshr.3806.1349
History: Received April 19, 1994 , Accepted April 25, 1995
 
Journal of Speech, Language, and Hearing Research, December 1995, Vol. 38, 1349-1355. doi:10.1044/jshr.3806.1349
History: Received April 19, 1994; Accepted April 25, 1995

This study evaluated the extent to which measures of lexical diversity (type-token ratio and number of different words produced) differentiated children with specific language impairment (SLI) from children whose language skills were following typical developmental expectations. Analysis of 50- and 100-utterance samples revealed that children with SLI did not significantly differ from their age- and language-equivalent peers on type-token ratio; however, children with SLI did use significantly fewer different words than their age-equivalent peers in these samples. When samples of 100 and 200 tokens were considered, the children with SLI also used significantly fewer different words than their age-equivalent counterparts. Overall, the findings of this study discourage the use of type-token ratio, as traditionally calculated, in many clinical and research activities related to children with SLI. In contrast, the number of different words produced provides a more sensitive and informative estimate of lexical diversity.

Acknowledgments
The participation of children and teachers from many preschools, day cares, and early intervention programs is gratefully acknowledged. Appreciation is also extended to the graduate students who assisted with aspects of language transcription and analysis, including: Claudia Davis, Jill Boyd, P. J. Seymour, and Beth Throneburg.
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