Measurement invariance of WISC-IV across normative and clinical samples

Measurement invariance of the WISC-IV second-order factorial structure between normative and clinical samples was investigated using WISC-IV core subtests and a total of 1100 children aged 6-16. Multi-group higher order analysis of mean and covariance structure (MG-MACS) models were used to analyze these data. Results supported measurement invariance. Only Coding and Comprehension subtest intercepts varied slightly between groups. The hypothesized WISC-IV factor model described the data well. Factor patterns, first- and second-order factor loadings, intercepts, residual variances of measured subtests, and disturbances of first-order factors of the WISC-IV were generally invariant. Results suggested that WISC-IV index scores and subtests have the same meaning for children in both normative and clinical groups.