Reliability and Practice Effects of Wisc-R Iq Estimates in a Normal Population

Abstract
WISC-R test-retest data with a six-month interval were obtained for 45 normal 10-year-old children ranging in age from 7.8 to 15.0 years. Verbal IQ estimates were stable (one IQ point increase), but significant practice effects were obtained on Performance and Full Scale IQ estimates (8 and 5 IQ point increases, respectively). Stability coefficients of .95, .89 and .95 for the Verbal, Performance and Full Scales, respectively, were as high as or higher than those reported on the WISC and by Wechsler on the standardization sample of 10-year-olds. Verbal subtests generally obtained a higher degree of test-retest reliability than Performance subtests, ranging from .59 to .88 and .54 to .78, respectively. Discussion focused on practical application of readministering the WISC-R. Regression formulas were computed to convert IQs to pretest equivalents.