CORE PROFILE TYPES FOR THE WISC-III AND WIAT - THEIR DEVELOPMENT AND APPLICATION IN IDENTIFYING MULTIVARIATE IQ-ACHIEVEMENT DISCREPANCIES

This study sought to identify the most representative ability and achi evement profiles for the Linking sample (N = 824) of the Wechsler Inte lligence Scale for Children-Third Edition (WISC-III; Wechsler, 1991) a nd the Wechsler Individual Achievement Test (WIAT; Wechsler, 1992). Th e primary benefit of such a core profile typology is that it provides contrasts for testing multivariate IQ-achievement discrepancies. The t ypology was constructed using factor indexes from the WISC-III (Verbal Comprehension, Perceptual Organization, Freedom from Distractibility, Processing Speed) and Composite scores from the WIAT (Reading, Mathem atics, Language, Writing). Scores from the WISC-III and WIAT were sort ed according to shape, level, and dispersion using a three-stage clust ering procedure that began with three separate agglomerative algorithm s and iterated the results from each. The iterated Ward's solution bes t met all formal heuristic and statistical criteria. The resultant six core profile types are described according to population prevalence, score configuration, overall ability and achievement levels, and trend s for parent and child demography. Thereafter, two methods are present ed for determining multivariate IQ-achievement discrepancies. Whereas the first is mathematically precise, the second is more convenient to every day practice. A step-by-step worksheet is provided for the ''eve ryday'' method and a case study is analyzed using this procedure.