More ups and downs of subtest analysis: Criterion validity of the DAS withan unselected cohort

This research evaluated the criterion-related validity of unusual subtest p rofiles from the Differential Ability Scales (Elliott, 1990). Three methods were used to identify unusual profiles: multivariate-nomothetic, univariat e-nomothetic, and univariate-ipsative prevalence rates less than or equal t o 5%. Participants were a large cohort (N = 1,200) stratified, within age l evels, in proportion to U.S. Census data on demography (e.g., race, gender, parents' educational levels). From this cohort, children with unusual prof iles were identified (n = 60) and matched to controls (n = 60) by the chara cteristics listed and overall IQs. The two groups were compared across a va riety of external criteria: (a) propensity for placement in special educati on, (b) three norm-referenced measures of achievement, and (c) six behavior al indices evaluated through standardized teacher ratings. Results showed n o group differences across all criteria, regardless of the method used to i dentify unusual subtest profiles. Findings are discussed in the context of the criterion validity of specific ability constructs.