An Alternate MLU Calculation Magnitude and Variability of Effects Research Article
Research Article  |   February 01, 2001
An Alternate MLU Calculation
 
Author Affiliations & Notes
  • Judith R. Johnston
    University of British Columbia Vancouver, British Columbia Canada
  • Contact author: Judith Johnston, PhD, School of Audiology and Speech Sciences, University of British Columbia, 5804 Fairview Avenue, Vancouver, B.C., V6T 1Z3, Canada. Email: jrj@audiospeech.ubc.ca
Article Information
Language Disorders / Specific Language Impairment / Language / Research Articles
Research Article   |   February 01, 2001
An Alternate MLU Calculation
Journal of Speech, Language, and Hearing Research, February 2001, Vol. 44, 156-164. doi:10.1044/1092-4388(2001/014)
History: Received April 11, 2000 , Accepted October 9, 2000
 
Journal of Speech, Language, and Hearing Research, February 2001, Vol. 44, 156-164. doi:10.1044/1092-4388(2001/014)
History: Received April 11, 2000; Accepted October 9, 2000
Web of Science® Times Cited: 50

This study investigated the effect of removing elliptical question responses, imitative utterances, and single-word Yes/No responses before calculating MLU. Forty-seven language samples from preschoolers with and without language impairment were analyzed. Initial MLUs ranged from 2.0 to 6.5 across both groups. The alternate calculation procedures resulted in an average 18% increase in the MLU index, with individual samples increasing as little as 3% or as much as 49%. The magnitude of the effect was primarily related to discourse properties, although in the SLI group there were secondary relationships to language level and proficiency. The observed variation in the discourse properties of language samples makes the alternate MLU index attractive to clinicians and researchers.

Acknowledgments
Support for this research came from the National Science and Engineering Research Council of Canada (OGP0138128). Expert assistance in data preparation and analysis was provided by Kelly Probert and Darryl Quantz.
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