Measurement Invariance of the Intelligence and Development Scales–2 Across Language Versions, Gender, and Age

Abstract

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.

Investigating the Relation of Intelligence and Executive Functions in Children and Adolescents with and without Intellectual Disabilities

“…The six-factor model suggested by Grieder and colleagues [ 36 ] showed a good fit in our sample (χ² (61) = 110.51, p < 0.001, RMSEA = 0.023, SRMR = 0.014, CFI = 0.994). An illustration of this model, including parameter estimates, can be found in Figure S1 .…”

“…Intelligence and EF are conceptualized as reflective measurement models following a factor analytic approach, proposing the latent variables as having a causal influence on their associated manifest indicators [ 68 ]. Regarding intelligence, the psychometric property of the proposed model has already been evaluated by Grieder and colleagues [ 36 ]. Therefore, the six-factor model identified by them served as the measurement model for intelligence, and its fit within our sample was reassessed utilizing a confirmatory factor analysis approach.…”

“…Empirically, the factors structure of the intelligence domain within the IDS-2 seems to differ from the theoretical model [ 35 , 36 ]. Grieder and Grob [ 35 ] identified only five primary intelligence factors within the standardization sample of the IDS-2 using exploratory factor analyses (EFA).…”

“…Their analyses indicated that the verbal reasoning and long-term memory tasks, as well as the visual processing and abstract reasoning tasks, loaded onto common factors that were named Semantic Long-Term Memory and Abstract Visual Reasoning, respectively. However, utilizing the confirmatory factor analyses (CFA) approach, Grieder and colleagues [ 36 ] identified a six-factor solution as the best fitting model in their study based on a Dutch and a German sample. This model reinstates the theoretically proposed separation of the Verbal Reasoning factor and the Long-Term Memory factor while allowing for a cross-loading of the Verbal Reasoning factor onto the “Story Recall” subtest.…”

“…We investigated whether the identified EF factor(s) could be integrated into the empirical model of the IDS-2 intelligence tasks proposed by Grieder and colleagues [ 36 ]. Based on past research, EF factors are closely linked to intelligence, and it can be assumed that a common EF factor might be comparable to other primary factors of intelligence.…”