Methodological Issues in the Calculation of Mean Length of Utterance (MLU)

South African Journal of Communication Disorders

Field Value
Title Methodological Issues in the Calculation of Mean Length of Utterance (MLU)
Creator Oosthuizen, Helena Southwood, Frenette
Subject — MLU calculation; MLU-w; MLU-m; Afrikaans; SLI
Description Mean length of utterance (MLU) is widely used as a diagnostic, monitoring and group matching measure. This study investigated methodological issues regarding the calculation of MLU. The aim was to establish whether different calculation procedures render different MLUs, and whether there is a high correlation between MLU measured in words (MLU-w) and in morphemes (MLU-m). Language samples from 15 Afrikaans-speaking 6-year-olds with and 15 without specific language impairment were analyzed. MLU was calculated eight times for each participant, varying sample size (50 or 100 utterances), unit counted (words or morphemes) and calculation method (traditional or alternate). Significant differences in resultant MLUs were due to the calculation method used, rather than sample size or unit counted. A high positive correlation (0.96) between MLU-w and MLU-m was found. The results imply that researchers and clinicians should clearly state their MLU calculation procedures, otherwise reliable comparisons between MLU scores from different sources cannot be made. The results furthermore imply that, in order to generalize research results and make diagnostic decisions based on MLU, consistent procedures should be used, not only with regard to language sampling, but also to MLU calculation.
Publisher AOSIS
Date 2009-12-31
Type info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion — —
Format application/pdf
Identifier 10.4102/sajcd.v56i1.194
Source South African Journal of Communication Disorders; Vol 56, No 1 (2009); 76–87 2225-4765 0379-8046
Language eng
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Rights Copyright (c) 2019 Helena Oosthuizen, Frenette Southwood