Early productive vocabulary predicts academic achievement 10 years later
We use a longitudinal design to examine associations for a diverse sample of 2,120 Danish 16 to 30 month old children between early expressive vocabulary and later reading and math outcomes in the sixth grade. Educational outcomes, in particular decoding and reading comprehension, can be predicted from an early vocabulary measure as early as 16 months with effect sizes (in proportion of variance accounted for) comparable to 1 year's mean growth in reading scores. The findings confirm in a relatively large population based study that late talkers are at risk for low educational attainment because the majority of children experiencing early language delay obtain scores below average in measures of reading in the sixth grade. Low scores have the greatest predictive power, indicating that children with early delays have elevated risk for later reading problems.