Measurement From a Hierarchical Point of View
There is ample empirical evidence that the structure of individual differences in cognitive abilities may be described in terms of a hierarchical model with three strata (Carroll, 1993; Gustafsson, 1988, Gustafsson & Undheim, 1996; Messick, 1992). From a taxonomic point of view the hierarchical approach has important advantages (Gustafsson, 1988), and it makes it possible to unite conflicting models that emphasize either one general ability (e.g., Spearman, 1927) or many specific abilities (e.g., Thurstone, 1938). But the hierarchical approach also may have implications for the measurement of cognitive abilities, and for measurement in general, which so far seem largely unexplored. The purpose of this chapter is to discuss possible implications of the hierarchical approach for measurement.