More Ups and Downs of Subtest Analysis: Criterion Validity of the DAS with an Unselected Cohort

This research evaluated the criterion-related validity of unusual subtest profiles from the Differential Ability Scales (Elliott, 1990). Three methods were used to identify unusual profiles: multivariate-nomothetic, univariate-nomothetic, and univariate-ipsative prevalence rates ≤ 5%. Participants were a large cohort (N = 1,200) stratified, within age levels, in proportion to U.S. Census data on demography (e.g., race, gender, parents' educational levels). From this cohort, children with unusual profiles were identified (n = 60) and matched to controls (n = 60) by the characteristics listed and overall IQs. The two groups were compared across a variety of external criteria: (a) propensity for placement in special education, (b) three norm-referenced measures of achievement, and (c) six behavioral indices evaluated through standardized teacher ratings. Results showed no group differences across all criteria, regardless of the method used to identify unusual subtest profiles. Findings are discussed in the context of the criterion validity of specific ability constructs.