Multi-group and hierarchical confirmatory factor analysis of the Wechsler Intelligence Scale for Children—Fifth Edition: What does it measure?

The purpose of this research was to test the consistency in measurement of Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V; Wechsler, 2014) constructs across the 6 through 16 age span and to understand the constructs measured by the WISC-V. First-order, higher-order, and bifactor confirmatory factor models were used. Results were compared with two recent studies using higher-order and bifactor exploratory factor analysis (Canivez, Watkins, & Dombrowski, 2015; Dombrowski, Canivez, Watkins, & Beaujean, 2015) and two using confirmatory factor analysis (Canivez, Watkins, & Dombrowski, 2016; Chen, Zhang, Raiford, Zhu, & Weiss, 2015). We found evidence of age-invariance for the constructs measured by the WISC-V. Further, both g and five distinct broad abilities (Verbal Comprehension, Visual Spatial Ability, Fluid Reasoning, Working Memory, and Processing Speed) were needed to explain the covariances among WISC-V subtests, although Fluid Reasoning was nearly equivalent to g. These findings were consistent whether a higher-order or a bifactor hierarchical model was used, but they were somewhat inconsistent with factor analyses from the prior studies. We found a correlation between Fluid Reasoning and Visual Spatial factors beyond a general factor (g) and that Arithmetic was primarily a direct indicator of g. Composite scores from the WISC-V correlated well with their corresponding underlying factors. For those concerned about the fewer numbers of subtests in the Full Scale IQ, the model implied relation between g and the FSIQ was very strong.