Construct validity of the WISC–IV Italian edition: A bifactor examination of the standardization sample: Chi niente sa, di niente dubita

Abstract

ABSTRACT This study utilized confirmatory factor analyses to examine the latent factor structure of the Wechsler Intelligence Scale for Children–Fourth Edition, Italian adaptation (WISC–IV Italian) standardization sample. One through five, oblique first-order factor models and higher-order as well as bifactor models were examined and compared using CFA. The bifactor model provided the best explanation of the scale’s factor structure. Across all models, general intelligence accounted for the largest amount of explained common variance, with group factors accounting for nonsignificant and trivial amounts of explained common variance. Omega-hierarchical subscale coefficients indicated that unit-weighted composites that would be generated by group factors would contain miniscule unique variance and therefore be of little clinical utility. Results are consistent with numerous empirical studies examining other European adaptations of the instrument and are at odds with the model put forward by the publisher. Clinicians who use the WISC–IV Italian adaptation are warned against attempting to interpret factor index scores independent of general intelligence.