An exploratory factor analysis of the Woodcock-Johnson IV tests of cognitive abilities and tests of oral language for the 9- to 13- year old age range
Scientific understanding of the nature of intelligence has steadily evolved over the years; however, the past century has seen an explosion of research aimed at understanding the construction of intelligence, the relationships between neuroscience and cognitive skills, and the best ways to measure intellectual abilities. While there is no clear consensus regarding the most accurate or all-encompassing theory of intelligence, Cattell-Horn-Carroll (CHC) theory has become one of the premiere guides to understanding the many facets of intelligence. The Woodcock-Johnson (WJ) series of tests have steadily incorporated CHC theory, aiming to provide practitioners with tangible measures of various cognitive skills. Two batteries from the most recent iteration of the WJ, the Woodcock-Johnson IV (WJ IV), are the WJ IV Tests of Cognitive Abilities (WJ IV COG) and the WJ IV Tests of Oral Language (WJ IV OL); WJ IV publishers purport that these two batteries provide a measure of general intelligence (g) as well as seven broad intelligence factors. However, research methods reportedly used to ensure adherence to CHC theory were both unorthodox and unclear. The purpose of this study is to use a commonly employed method of observing test structure – exploratory factor analysis – to understand the factor structure of the WJ IV COG and WJ IV OL for the 9- to 13- year old age group. A correlation matrix provided in the WJ IV Technical Manual was used for data analyses. Four subtests were removed from analyses due to weak or cross-loadings, thus the final solution was comprised of 23 subtests. Results indicated that the WJ IV COG and WJ IV OL are primarily measures of a single strong factor which coincides with comprehension-knowledge (Gc). Four additional weaker but salient factors were also present and hypothesized to represent short-term working memory (Gwm), perceptual reasoning, processing speed (Gs), and auditory processing (Ga). Perceptual reasoning was the only factor which did not clearly align with the factor structure reported in the Technical Manual, as it appeared to represent a blend of fluid reasoning (Gf), long-term storage and retrieval (Glr), and visual processing (Gv). These results closely mirrored the findings of other researchers examining the structural validity of the WJ IV.