Two groups of 3-year-olds, 17 with language impairment and 17 with typical language, participated in a picture description task. Percentage Grammatical Utterance (PGU), Percentage Sentence Point (PSP), and Percentage Verb Tense Usage (PVT) were computed. PGU, PSP, and PVT were all sensitive to language impairment. However, PGU was less likely than PSP and PVT to misclassify children with typical language. The resultant diagnostic accuracy makes PGU an appropriate measure to use to screen for language impairment.
Eisenberg, Sarita L. & Guo, Ling-Yu. (2013). Differentiating children with and without language impairment based on grammaticality. Language, Speech, and Hearing Services in Schools, 44, 20-31.