DISCOVERING CORE PROFILE TYPES IN THE SCHOOL-AGE STANDARDIZATION SAMPLE OF THE DIFFERENTIAL ABILITY SCALES

The ability profiles most representative of the school-age norm group for the Differential Ability Scales (DAS; Elliot, 1990a), an individua lly administered test of cognitive skills, are identified and describe d. The cognitive subtest profiles of the 2,400 children aged 6 to 17 y ears who comprise the DAS national sample were sorted based on their l evel, shape, and dispersion using multistage hierarchical cluster anal yses with independent replications. Seven core profile types were disc overed that adequately met established heuristic and statistical crite ria, including acceptable internal cohesion, external isolation, repli cability, shortterm stability, and full coverage of the sample. Each p rofile type was described in terms of prevalence and constituent child ren's characteristics (i.e., overall differential ability, academic ac hievement, and distinguishing prevalence trends for age, sex, race/eth nicity, and parent education). Discussion showed how the typology prov ides clinicians and researchers with the necessary contrasts against w hich to evaluate claims regarding the distinctiveness and potential di agnostic and treatment utility of specific DAS profiles. Included are three methods for assessing the uniqueness of any DAS profile: two met hods appropriate for research and one suited for clinical practice.