Estimation of the Differences Between WISC-R and WISC IQS

Abstract

The purpose of the study was to estimate the magnitude of the differences between IQs obtained from WISC-R and those from the original WISC. The 1949 WISC and the 1974 WISC-R were reviewed to identify a common core of items. Regression equations were developed for the 1949 sample, by age level, to predict WISC IQs from the common core. These equations were then used to estimate the WISC IQs of those in the WISC-R standardization sample. In the age range 6½ to 15½ years, the Full Scale IQs on WISC-R were 4 points lower, on the average, than WISC IQs. The difference, however, varied with the particular IQ Scale (Verbal or Performance), age, and ability level.