Factorial invariance of the Wechsler Intelligence Scale for Children, Fifth Edition, across the UK, US and Australia & New Zealand.

OBJECTIVES: This study examined the factorial invariance of the factor structure of the Wechsler Intelligence Scale for Children, Fifth Edition (WISC-V) across the UK, US and Australia & New Zealand (A&NZ). The factorial equivalence of cognitive assessments should be demonstrated before assuming cross-culture generalizability and interpretations of score comparisons. METHODS: Data were obtained from the UK, US and A&NZ normative standardizations of the WISC-V. The samples consisted of 415 UK, 2200 US and 528 A&NZ children, aged 6-16. Confirmatory factor analysis was applied separately in each sample to establish the baseline model. Next, tests of factorial invariance were undertaken using the recommended hierarchical approach, firstly across the UK and A&NZ samples and then across the UK and US samples. RESULTS: The five-factor first-order scoring model was found to be excellent fit across all three samples independently. Strict factorial invariance of the WISC-V was demonstrated firstly across the UK and A&NZ and secondly the UK and US nationally representative standardization samples. Comparison of latent means found small but significant differences in female children across the UK and A&NZ samples. CONCLUSIONS: Consistent with previous research, these results demonstrate the generality of the WISC-V factor structure across the UK, US and A&NZ. Furthermore, as the WISC-V factor structure aligns with the Cattell-Horn-Carroll (CHC) model of cognitive abilities, the results add further support to the cross-cultural generalizability of the CHC model. Small but significant differences in latent factor scores found across samples support the development and use of local normative data.

Some supplementary methods for the analysis of WAIS-IV index scores in neuropsychological assessment.

OBJECTIVES: To develop supplementary methods for the analysis of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) in neuropsychological assessment. DESIGN AND METHODS: Psychometric. RESULTS: The following methods are made available: (a) provision of traditional confidence intervals (CIs) on index scores, (b) expression of the endpoints of CIs as percentile ranks; (c) quantification of the number of abnormally low index scores exhibited by a case and accompanying estimate of the percentage of the normative population expected to exhibit at least this number of low scores; (d) quantification of the reliability and abnormality of index score deviations from an individual's index score mean (thereby offering an alternative to the pairwise approach to index score comparisons available in the WAIS-IV manual); (e) provision of CIs on an individual's deviation scores or pairwise difference scores, (f) estimation of the percentage of the normative population expected to exhibit at least as many abnormal deviations or abnormal pairwise differences as a case; and (g) calculation of a case's Mahalanobis distance index (MDI), thereby providing a multivariate estimate of the overall abnormality of an index score profile. With the exception of the MDI, all the methods can be applied using tables provided in this paper. However, for ease and speed of application, and to reduce the possibility of clerical error, all the methods have also been implemented in a computer program. CONCLUSIONS: The methods are useful for neuropsychological interpretation of the WAIS-IV.