CONSTRUCT AND CRITERION-RELATED VALIDITY OF THE WISC-III FOR EXCEPTIONAL STUDENTS AND THOSE WHO ARE AT RISK

Using an ''at-risk'' and special-education sample, this study investigated the validity of the WISC-III. Derived IQs generally differentiated among samples of exceptional children. The Wechsler concept of global intelligence, or g, and the WISC-III four-factor model were supported overall. Symbol Search loaded highest on Processing Speed (PS); however, Picture Arrangement loaded almost exclusively on PS contrary to prior results. PS appeared to be associated with visual-motor/sequential processing with a timed component. When the relationships among the WISC-III and the DTLA-3, PPVT-R, WRAT-R, and Piers-Harris were examined, support for the overall validity of the WISC-III was evidenced. Verbal measures tended to exhibit higher validity correlations and comprised factor 1 of the multitest factor analysis. Factors 2 and 3 were associated with nonverbal abilities, and factor 4 appeared to be achievement related. Further research is needed to extend the knowledge-base of the validity of the WISC-III, including its factor structure and functional utility.