Construct Validity of the WISC–IV With a Large Referred Irish Sample

Irish educational psychologists frequently use the Wechsler Intelligence Scale for Children– Fourth U.K. Edition (WISC–IV) in clinical assessments of children with learning difficulties. Unfortunately, reliability and validity studies of the WISC–IV have not yet been reported. This study examined the construct validity of WISC–IV core subtest scores obtained from evaluations to assess learning difficulties in 794 Irish children (494 boys and 300 girls). One through four first-order factor models and indirect (higher-order) versus direct (bi-factor) hierarchical models were examined and compared using confirmatory factor analyses. The oblique four-factor Wechsler model provided the best fit to these data, but meaningful differences in fit statistics were not observed between this oblique four-factor model and rival indirect hierarchical and direct hierarchical models. For theoretical reasons, the direct (bi-factor) hierarchical model provided the best explanation of the WISC–IV factor structure. The general factor accounted for 63.7% of the common variance, whereas first-order factors each accounted for 8.6% to 9.6% of the common variance. Thus, the results with referred Irish children were similar to those from other investigations, further demonstrating the replication of the Wechsler Intelligence Scale for Children–Fourth Edition factor structure across cultures and the importance of focusing primary interpretation on the Full Scale Intelligence Quotient.