The higher order structure of the WISC–IV Italian adaptation using hierarchical exploratory factor analytic procedures

Abstract

ABSTRACTThe factor structure of the Wechsler Intelligence Scale for Children–Fourth Edition, Italian adaptation (WISC-IV Itaian; Orsini, Pezzuti, & Picone, 2012; Wechsler, 2012) standardization sample was examined with exploratory factor analytic methods (EFA) not included in the Technical Manual. Principal-axis extraction followed by oblique rotation using five-, four-, three-, and two-factor solutions all produced relatively similar results. None of the extraction criteria supported the retention of four factors, as suggested by the WISC–IV Italian Technical Manual. However, when the four-factor structure was subjected to second-order factor analysis and transformed with the Schmid and Leiman (1957) orthogonalization procedure, the hierarchical g factor accounted for large portions of total and common variance, while the four first-order group factors accounted for small portions of total and common variance, rendering interpretation at the factor index level of questionable value. Clinicians who use the WISC-IV Italian should recognize the strong measurement of general intelligence yielded by the scale and clinical interpretation should avoid the overinterpretation of factor index scores that conflate group factor variance with general intelligence variance.