Relationship Between Children's Lexical Diversity in Written Narratives and Performance on a Standardized Reading Vocabulary Measure.

The purpose of this study was to examine construct validity of methods of calculating lexical diversity in written narrative samples relative to children's performance on a reading vocabulary measure. For 234 children in 1st-5th grade, written narratives were examined and compared between grades for number of different words (NDW), total words (TNW), NDW in a truncated 50 word sample, and type token ratio (TTR). The relationship between lexical diversity in written narratives and a standardized reading vocabulary measure (GMRT-4) was analyzed by comparing correlations. Grade differences were observed in measures of lexical diversity and productivity. Lexical diversity showed a significant moderate correlation with the GMRT-4. NDW had a stronger relationship to GMRT-4 scores than TTR for participants in first and second grade. Considering length (TNW, NDW constrained to 50 words, or TTR) did not result in a stronger relationship with reading vocabulary. Following additional study establishing probe equivalence, NDW in written narratives may be an efficient, educationally relevant, marker of language maturity and a good predictor of performance on a standardized reading vocabulary measure.