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)

The investigation examined the "Wide Range Achievement Test" (WRAT) and its subtests (spelling, reading, and arithmetic), as well as possible differences attributable to the factors of sex, with the "Chicago Non-Verbal" (CNV) as a criterion variable. The 1970 study encompassed 72 Indian students (with a mean chronological age…