Discovering Core Profile Types in the School-Age Standardization Sample of the Differential Ability Scales

Abstract

The ability profiles most representative of the school-age norm group for the Differential Ability Scales (DAS; Elliot, 1990a), an individually administered test of cognitive skills, are identified and described. The cognitive subtest profiles of the 2,400 children aged 6 to 17 years who comprise the DAS national sample were sorted based on their level, shape, and dispersion using multistage hierarchical cluster analyses with independent replications. Seven core profile types were discovered that adequately met established heuristic and statistical criteria, including acceptable internal cohesion, external isolation, replicability, short-term stability, and full coverage of the sample. Each profile type was described in terms of prevalence and constituent children's characteristics (i.e., overall differential ability, academic achievement, and distinguishing prevalence trends for age, sex, race/ethnicity, and parent education). Discussion showed how the typology provides clinicians and researchers with the necessary contrasts against which to evaluate claims regarding the distinctiveness and potential diagnostic and treatment utility of specific DAS profiles. Included are three methods for assessing the uniqueness of any DAS profile: two methods appropriate for research and one suited for clinical practice.