WAIS and neuropsychological tests: common and unique variance within an epileptic population.

Neuropsychological assessment batteries, which traditionally require lengthy administration times, may be composed of multiple tests which measure essentially the same performance attributes. Test redundancies of this nature compromise the adequacy of a test battery from a cost containment perspective. The present study evaluated the common and unique variance of the WAIS relative to a modified and expanded Halstead-Reitan test battery to determine if information obtained from the WAIS is sufficiently nonredundant to justify its inclusion as part of this assessment battery. Cross-validated estimates of bivariate and multivariate relationships between these instruments were generated from two samples (n = 125) of epileptics. Results indicated statistically significant redundancies, yet, when interpreted from a clinical perspective it was evident that neuropsychological tests could not accurately duplicate information provided by the WAIS. Accordingly, it was not recommended that the WAIS be eliminated from this test battery in order to reduce test administration time.