Confir Rmatory Factor Analysis of the WISC-III for Students with Learning Disabilities

Abstract

This study conducted confirmatory factor analyses to examine 12 competing models that attempt to explain the underlying latent constructs measured by the Wechsler Intelligence Scale for Children-Third Edition (WNISC-III) in a sample of 1,201 students with learning disabilities (721 White and 480 Nonwhite). Models were selected based upon theoretical explanations of the WISC-III factor structure as well as from previously conducted empirical research conducted on the W7ISC-III normative sample and with independent samples of students with exceptionalities. For both White and Nonwhite groups, four models could not be statistically distinguished from one another based upon overall fit statistics. Plausible models included the traditional first-order four-factor oblique structure of the standardization sample, the hierarchical second-order model with four first-order factors favored by Keith and Witta (1997), a bifactor second-order model with four first-order factors described by Gustafsson and Undheim (1996), and a bifactor second-order model with three first-order factors. Current results add to a growing body of evidence suggesting that WISC-III Verbal Comprehension, Perceptual Organization. and Processing Speed factors are robust across samples but the Freedom from Distractibility factor demonstrates tenuous construct validity.