Though some unexpected sex differences were discovered, the two diagnostic categories were not found to be psychometrically distinct. Further, the results of a longitudinal analysis suggested that, while IQ scores remained relatively stable over time within a subset of the original sample, achievement scores definitely declined. (Author)

A wide array of data was gathered in a nationwide study, including parent and child interviews, intelligence test and achievement test scores, and teacher ratings of children's classroom performance. Results indicated extensive differences favoring intact family children, which persisted when IQ and socioeconomic status measures were controlled.…