Language ability was measured as the child’s percentile score on the composite language section of a nationally-normed standardized test, which was collected annually via official school records. A school records form with achievement test scores for the participants was completed by a school administrator. The school records were collected at the end of the school year in the summer, but the standardized tests were administered during the school year. School records from ages 7–10 were collected when the children were 10 years old, and school records from ages 11–13 were collected in the summer after each school year. The composite language ability score reflected two types of subtests, including language mechanics and language expression. Correlations between language mechanics and expression scores ranged from .59 to .71 (p < .001) depending on the year. Language ability was averaged within time frame.
