WISC-R factor reliability at 11 age levels

The reliability coefficients of the normative WISC‐R factors (Verbal Comprehension, Perceptual Organization, Freedom from Distractibility) were computed for each age level of the standardization sample from a formula provided by Tellengen and Briggs (1967). Results indicated that the Verbal Comprehension and Perceptual Organization factors possess generally equivalent reliability to their analogous intelligence quotients. Freedom from Distractibility possesses adequate reliability for routine clinical interpretation. Criticisms of the reliability of the third factor (Distractibility) as being too low for individual assessment appear unwarranted. A table of reliability coefficients is presented for each age level in the standardization sample.