On Methodology in the Study of Cognitive Abilities

From experiences in reanalyzing some 480 datasets in the factor-analytic literature of cognitive abilities (Carroll, 1993a), 1 report and defend opinions 1 have formed about methodological problems in this field - in particular with regard to: (a) study design in relation to the structure of cognitive abilities, (b) test design in relation to IRT procedures, factorial complexity, and cognitive processes; (c) separate treatment of level and speed aspects of ability; (d) the respective roles of exploratory and confirmatory techniques; and (e) the respective roles of principal component and principal factoring techniques, with suggestions concerning iterative procedures and the number-of-factors problem.