An Epidemiological-Cohort Study of DAS Processing Speed Factor: How Well Does it Identify Concurrent Achievement and Behavior Problems?

Abstract

This study evaluated the criterion-related validity for the Speed of Processing (SP) factor of the Differential Ability Scales (DAS; Elliott, 1990). The SP factor is comprised of one subtest score (Speed of Information Processing) based on results from factor analyses. Participants were an epidemiological sample (N= 1,400) stratified, within age levels, in proportion to census data on demography (e.g., race, gender, parents' educational levels). From this cohort, groups with unusual SP strengths and SP weaknesses were identified using General Cognitive Ability (GCA) scores from the DAS as contrasts (i.e., SP>GCA and GCA>SP differences at a population prevalence < 5%). The SP>GCA group (n= 60) and the GCASP group (n = 60) were matched to respective controls (where each control n = 60) on the demographic variables listed above and GCAs. Each group and its control were compared across three norm-referenced measures of achievement and six teacher-rated indices of behavioral adjustment. Comparisons failed to show significant differences on any criterion variable. Results are discussed in the context of how well epidemiological samples evaluate the validity of ability profiles and the need for future research to use more representative measures of processing speed (i.e., those with two or more subtests contributing to the factor).