Article/Report  |   August 2006
Mean Length of Utterance in Children With Specific Language Impairment and in Younger Control Children Shows Concurrent Validity and Stable and Parallel Growth TrajectoriesRice et al.: MLU Holds Up Over Time
 
Author Notes
  • Contact author: Mabel L. Rice, 1000 Sunnyside Avenue, 3031 Dole Center, Child Language Doctoral Program, University of Kansas, Lawrence, KS 66045. E-mail: mabel@ku.edu
  • Lesa Hoffman is now at University of Nebraska—Lincoln.
    Lesa Hoffman is now at University of Nebraska—Lincoln.×
Article Information
Language Disorders / Specific Language Impairment / Language
Article/Report   |   August 2006
Mean Length of Utterance in Children With Specific Language Impairment and in Younger Control Children Shows Concurrent Validity and Stable and Parallel Growth TrajectoriesRice et al.: MLU Holds Up Over Time
Journal of Speech, Language, and Hearing Research, August 2006, Vol. 49, 793-808. doi:10.1044/1092-4388(2006/056)
History: Received February 28, 2005 , Revised September 4, 2005 , Accepted December 6, 2005
 
Journal of Speech, Language, and Hearing Research, August 2006, Vol. 49, 793-808. doi:10.1044/1092-4388(2006/056)
History: Received February 28, 2005; Revised September 4, 2005; Accepted December 6, 2005
Web of Science® Times Cited: 50

Purpose: Although mean length of utterance (MLU) is a useful benchmark in studies of children with specific language impairment (SLI), some empirical and interpretive issues are unresolved. The authors report on 2 studies examining, respectively, the concurrent validity and temporal stability of MLU equivalency between children with SLI and typically developing children.

Method: Study 1 used 124 archival conversational samples consisting of 39 children with SLI (age 5;0 [years;months]), 40 MLU-equivalent typically developing children (age 3;0), and 45 age-equivalent controls. Concurrent validity of MLU matches was examined by considering the correspondence between MLU and developmental sentence scoring (DSS), index of productive syntax (IPSyn), and MLU in words. Study 2 used 205 archival conversational samples, representing 5 years of longitudinal data collected on 20 children with SLI (from age 5;0) and 18 MLU matches (from age 3;0). Evaluation of growth dimensions within and across groups was carried out via growth-curve modeling.

Results: In Study 1, high levels of correlation among the MLU, DSS, and IPSyn measures were observed. Differences between groups were not significant. In Study 2, temporal stability of MLU matches was robust over a 5 year period.

Conclusions: MLU appears to be a reliable and valid index of general language development and an appropriate grouping variable from age 3 to 10. The developmental stability of MLU matches is indicative of shared underlying growth mechanisms.

Acknowledgments
This study was supported by National Institute on Deafness and Other Communication Disorders Award R01 DC01803. Further support was provided by grants from the National Institutes of Health to the University of Kansas through the Mental Retardation and Developmental Disabilities Research Center (P30HD002528), the Center for Biobehavioral Neurosciences in Communication Disorders (P30DC005803), and R01DC005226.
We express special appreciation to Karla Barnhill and Shannon Wang for their assistance in data collection. Our special appreciation is expressed to the children, parents, and teachers who participated in this study, and to the following schools who supported this research: Edgerton Elementary in Edgerton, KS; Allen Elementary, Avenue A Elementary, Morgan Elementary School, Stafford Elementary, South Hutchinson Elementary, and Union Valley Elementary in Hutchinson KS; Centennial Elementary, Deerfield Elementary, Hillcrest Elementary, Hilltop Child Development Center, Kennedy Elementary, New York Elementary, Quail Run Elementary, St. John’s Elementary, Sunflower Elementary, Sunset Hills Elementary, and Wakarusa Valley Elementary in Lawrence, KS; Meadow Lane Elementary in Lee’s Summit, MO; Scarborough Elementary in Olathe, KS; Garfield Elementary, Hawthorne Elementary, and Lincoln Elementary in Ottawa, KS; Holy Trinity Elementary, Nativity Parish in Overland Park, KS; and Wellsville Elementary in Wellsville, KS.
Order a Subscription
Pay Per View
Entire Journal of Speech, Language, and Hearing Research content & archive
24-hour access
This Article
24-hour access