Cluster subtypes in the WISC-III standardization sample: Analysis of factor index scores.

Representative profile subtypes, based on factor index scores, were examined in the standardization sample of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; Wechsler, 1991). Two-stage cluster analysis identified 5 reliable subtypes. Three of these were differentiated by levels of performance (ranging from below average, to average, to above average); the other 2 were characterized by patterns of performance, with relative efficacy on the processing speed factor being the most prominent distinction (ranging from a relative weakness to a relative strength). The cluster subtypes did not differ significantly in age, but parental level of education covaried directly with level of WISC-III performance. A method for determining the relative uniqueness of clinically obtained WISC-III factor index score patterns is presented.