Inter-subtest scatter in the WAIS-R standardization sample

Abstract

To be able to evaluate the possible diagnostic significance of the magnitude of subtest-to-subtest scatter on the Wechsler Adult Intelligence Scale—Revised (WAIS-R), it is important to know the frequency of various levels of scatter in the general population. To provide this information, the magnitude of scatter across all 11 subtests, and across the subtests of the Verbal and Performance scales, was computed for each of the 1,880 individuals used in the WAIS-R standardization. The range (difference between highest and lowest subtest scaled scores) was found to be an effective measure of scatter when compared with other, more complex indices. Scaled score scatter, which ranged from 2 to 16 points on the Full Scale, averaged 6.7 points for the Full Scale and 4.7 points each for the Verbal and Performance scales. Scatter had little relationship to age, sex, race, and years of education completed. However, the average amount of scatter increased substantially with IQ level. Normative tables for interpreting scatter are provided, and implications of these findings for the practitioner, especially in neuropsychology, are discussed.