Comparison of two abbreviated models of the WISC-R

Abstract

A comparison of two WISC-R short form models was made to determine the adequacy of each and the possible superiority of one. Data from 192 psychiatric and 200 special education subjects were used to compare Kennedy and Elder's (1982) regression model with Kaufman's (1976) linear equating model. In addition, a regression-derived prediction formula determined from each sample was used to predict FSIQs for the other sample. Correct and incorrect classifications were analyzed for the accuracy of estimate. The percentage of correct classifications for the AAMD Scheme (Heber, 1976) was high for all prediction formulae, and none of the differences was statistically reliable. Correct classification for the Wechsler System (Wechsler, 1974) were more variable, but no differences were statistically significant. Both the Kennedy and Elder, and the Kaufman abbreviated forms attained a high degree of association (K, = .67 to .89). It was concluded, therefore, that both models were equally effective.The Wechsler Intelligence Scale for Children, Revised (WISC-R; Wechsler, 1974) is today the intelligence test most widely used with children. It currently is employed for initial and reevaluation purposes in schools, hospitals, and private practice settings. The WISC-R is an expensive testing device because of the time necessary for its administration, scoring, and interpretation. Because of the breadth of information that the complete WISC-R provides, it is used whenever possible in initial evaluations, but for screening, research, and reevaluation purposes, the full-scale IQ (FSIQ) often provides the most essential piece of information. The FSIQ then is combined with knowledge obtained from other tests, interviews, and observations. In these instances, an abbreviated form that accurately predicts the FSIQ would be more cost effective and, therefore, an invaluable instrument.

Equal weighting vs. differential weighting of subtest scores on short forms of Wechsler's intelligence scales

“…The short forms selected for investigation were as follows: -The five-subtest short form of the WISC-R (Information, Block Design, Comprehension, Picture Arrangement, and Coding) first proposed by Kennedy and Elder (1982) and since employed by Beck et al (1983), Phelps and Rosso (1986), Vollmerhausen et al (1986), Wade, Phelps, and Falasco (1986), and Zimet, Farley, and Dahlem (1985). This short form was chosen because of its current popularity and also because Zimet et al (1985) took the unusual step of obtaining multiple regression weights based on their own data.…”

“…Since then, the Wechsler Intelligence Scale for Children-Revised (WISC-R; Wechsler, 1974) has replaced the WISC, and several investigators have proposed short forms of that scale that involve differential weighting (Beck, Ray, Seidenberg, Young, & Gamache, 1983;Clarizio & Veres, 1984;Kennedy & Elder, 1982;Vollmerhausen, Elder, & Clark, 1986). Today, we also have the Wechsler Preschool and Primary Scale of Intelligence (WPPSI; Wechsler, 1967) and the Wechsler Adult Intelligence Scale-Revised (WAIS-R; Wechsler, 1981), and although no one appears to have suggested a short form of either the WPPSI or the WAIS-R that involves differential weighting, the question posed earlier is potentially relevant to short forms of those scales as well.…”