Age and sex invariance of the International Cognitive Ability Resource (ICAR)

To encourage broader assessment of cognitive abilities in research across scientific fields, Condon and Revelle (2014) developed the first cognitive assessment in the public domain, the International Cognitive Ability Resource (ICAR). Despite initial support for its psychometric properties, little is known about the construct validity of the ICAR across distinct groups of individuals. In order to meaningfully interpret ICAR scores across diverse populations, measurement invariance must be established. To this end, a multiple group confirmatory factor analysis (MGCFA) was conducted on the full 60-item ICAR (ICAR60) and the 16-item Sample Test (ICAR16) to test for invariance across self-reported biological sex and age groups. A moderated nonlinear factor analysis (MNLFA) was conducted on the ICAR16 to test for differential item functioning (DIF) across linear age, age squared, sex, and their respective interaction terms. The baseline MGCFA models proposed by the test developers fit the data well for males and females and across age groups based on the fit indices Mc, CFI, TLI, and RMSEA. In the MCGFA, both forms demonstrated acceptable changes in the Mc (∆< .02) and CFI (∆< .01) in both loading- and threshold-constrained models for the sex and age group models. The MNLFA supported the weak and strong measurement invariance of the ICAR16 found in the MGCFA; no meaningful differences in item thresholds or factor-loadings were found across age, sex, or their interaction terms. Overall findings provide evidence that both forms measure the same constructs across sex and age, and the same strength of the relations exists among the first-order factors and the items. Despite these findings, the internal consistency of the subscales suggests only the total score of the ICAR16 be used for research; those interested in the subscales of the ICAR are advised to use the ICAR60.