A confirmatory factor analysis of the WISC-III in a clinical sample with cross-validation in the standardization sample.

Maximum likelihood confirmatory factor analysis was applied to the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; Wechsler, 1991) data of a mixed clinical sample of 318 children. Analyses were designed to determine which of nine hypothesized oblique factor solutions could best explain intelligence as measured by the WISC-III in the clinical sample. Competing latent variable models were identified in previous studies, and results in the clinical sample were cross-validated by testing all models in the WISC-III standardization sample (n = 2200). Findings in both the clinical and standardization samples supported a five-factor model including Verbal Comprehension, Constructional Praxis, Visual Reasoning, Freedom from Distractibility, and Processing Speed factors. The Visual Reasoning factor was defined primarily by Picture Arrangement, whereas Mazes did not appear to improve model fit. Potential opportunities and pitfalls with regard to the interpretation of the proposed Visual Reasoning factor are discussed.