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The factor structure of the intelligence and scholastic skills domains of the Intelligence and Development Scales–2 was examined using exploratory factor analyses with the standardization and validation sample ( N = 2,030, aged 5 to 20 years). Results partly supported the seven proposed intelligence group factors. However, the theoretical factors Visual Processing and Abstract Reasoning as well as Verbal Reasoning and Long-Term Memory collapsed, resulting in a five-factor structure for intelligence. Adding the three scholastic skills subtests resulted in an additional factor Reading/Writing and in Logical–Mathematical Reasoning showing a loading on abstract Visual Reasoning and the highest general factor loading. A data-driven separation of intelligence and scholastic skills is not evident. Omega reliability estimates based on Schmid–Leiman transformations revealed a strong general factor that accounted for most of the true score variance both overall and at the group factor level. The possible usefulness of factor scores is discussed.

The latent factor structure of the German Wechsler Intelligence Scale for Children–Fifth edition (German WISC-V) was examined using complementary hierarchical exploratory factor analyses (EFAs) with Schmid and Leiman transformation and confirmatory factor analyses (CFAs) for all reported models from the German WISC-V Technical Manual and rival bifactor models using the standardization sample ( N = 1,087) correlation matrix of the 15 primary and secondary subtests. EFA results did not support a fifth factor (Fluid Reasoning). A four-factor model with the dominant general intelligence ( g) factor resembling the WISC-IV was supported by EFA. CFA results indicated the best representation was a bifactor model with four group factors, complementing EFA results. Present EFA and CFA results replicated other independent assessments of standardization and clinical samples of the United States and international versions of the WISC-V and indicated primary, if not exclusive, interpretation of the Full Scale IQ as an estimate of g.

We examined the factor structure of the intelligence and basic skills domains of the Intelligence and Development Scales–2 (IDS-2) and measurement invariance across the Dutch and German versions, sex, and age with confirmatory factor analyses and local structural equation modeling of the standardization samples. Of several theoretically and empirically determined models, a second-order model with six first-order factors best represented the Dutch IDS-2 structure. Five IDS-2 factors were confirmed, but Visual Processing and Abstract Reasoning and the intelligence and basic skills domains were not separable. This final model displayed full invariance across the Dutch and German versions and partial scalar invariance across sex, and it appeared largely invariant across ages 7 to 20 years. The strong general intelligence factor and weak broad ability factors suggest individual interpretation should mainly be based on the full-scale IQ. We discuss the importance of testing multiple plausible models and implications for theory and practice.

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