Kristof Kovacs

Although many fluid reasoning (Gf) tests have been developed, there is a lack of figural tests measuring its lower-order process factors simultaneously. The present article introduces the development of the Multidimensional Induction-Deduction Computerized Adaptive Test (MID-CAT) to measure two process factors of Gf. The MID-CAT is designed to provide an instrument that is flexible, efficient, and entirely free for non-commercial use. We created 530 items and administered them to a sample of N = 2,247. Items were fitted and calibrated using the Rasch model. The results indicate that the final item pool has a wide range of difficulties that could precisely measure a wide range of test-takers’ abilities. A simulation study also indicates that MID-CAT provides greater measurement efficiency than separate-unidimensional CAT or fixed-item test. In the discussion, we provide perspectives on how the MID-CAT can be used for future research.

William Stern is mostly renowned for inventing the IQ formula. However, he is also the originator of the term ‘differential psychology’ itself. His program of differential psychology synthesized population-based correlational studies as well as idiosyncratic approaches focusing on unique profiles of individuals. We argue that his approach still offers valuable ideas to this day; in particular, the individualistic sub-programme of Stern’s differential psychology corresponds to a large extent to ipsative testing that emphasizes a profile-based analysis of individual strengths and weaknesses.