The reliability of score differences on the WAIS,WISC-R,and WAIS-R

Analyzed data from the WAIS, WISC-R, and WAIS-R manuals to determine the reliabilities of the differences between Verbal and Performance IQs, of subtest comparisons, and of differences between subtest and IQ scores. The differences between the Verbal and Performance IQs were moderately reliable: 0.76 (WAIS and WISC-R) and 0.81 (WAIS-R). The means of the reliability coefficients of the differences between the 55 pairs of subtests were appreciably lower: 0.58 (WAIS), 0.62 (WISC-R), and 0.65 (WAIS-R). The most consistently reliable subtest differences were between Block Design and Vocabulary and the least reliable differences between Block Design and Object Assembly. The means of the reliability coefficients of the differences between subtest scores and the Full Scale IQs were 0.53 (WAIS), 0.58 (WISC-R), and 0.62 (WAIS-R). It was concluded that caution should be exercised when interpreting configurations on Wechsler protocols.