Measuring productive vocabulary of toddlers in low-income families: concurrent and predictive validity of three sources of data.

This study examined parental report as a source of information about toddlers' productive vocabulary in 105 low-income families living in either urban or rural communities. Parental report using the MacArthur Communicative Development Inventory - Short Form (CDI) at child age 2 ; 0 was compared to concurrent spontaneous speech measures and standardized language assessments, and the utility of each source of data for predicting receptive vocabulary at age 3 ; 0 (Peabody Picture Vocabulary Test) was evaluated. Relations between language measures of interest and background variables such as maternal age, education, and race/ethnicity were also considered. Results showed that for the sample as a whole, parental report was moderately associated with other language measures at age 2 ; 0 and accounted for unique variance in PPVT at age 3 ; 0, controlling for child language skills derived from a standard cognitive assessment. However, predictive validity differed by community, being stronger in the rural than in the urban community. Implications of significant differences in background characteristics of mothers in the two sites are discussed.