Validating Rules: A non-verbal free fluid intelligence test

Intelligence is one of the strongest predictors of academic achievement. Fluid intelligence is one part of the construct, that can be measured by deductive and inductive reasoning. We set up a validation study of a free, non-verbal fluid intelligence test (Rules) in the context of study orientation. In this study, we investigate the reliability, distribution and structural validity of Rules, consisting of 28 items. Evidence from confirmatory multidimensional item response theory models suggests structural validity of the non-verbal reasoning test. For construct validity, a cross-validation between Rules and Raven's 2 Progressive Matrices in a sample of 235 last-year secondary school students resulted in a correlation of 0.62. Furthermore, we analyzed the predictive validity of the non-verbal reasoning test, which was administered to 32,585 last-year secondary school students. A standardized mathematics and language test were administered as a proxy for academic achievement scores. The results confirmed the predictive validity of the non-verbal reasoning test for cognitive achievement, with correlations of r = 0.61 for mathematics and r = 0.41 for language. Findings support the use of Rules in psychological practice, in particular for large-scale study exploration tools and low-stakes testing as a proxy for cognition or fluid reasoning.