This study examined the underlying constructs measured by the Differential Ability Scales (DAS; C.D. Elliott, 1990a) as they relate to the Cattell‐Horn‐Carroll (CHC) Theory (K.S. McGrew, 1997) of cognitive abilities. The DAS and Woodcock‐Johnson Tests of Cognitive Abilities (WJ‐III COG; R.W. Woodcock, K.S. McGrew, & N. Mather, 2001) were administered to 131 children in grades 3 through 5 who took part in a concurrent validity study included in the Woodcock‐Johnson Tests of Cognitive Abilities, Third Edition, technical manual (K.S. McGrew & R.W. Woodcock, 2001). Confirmatory factor analyses using maximum likelihood estimation were conducted with the AMOS 5.0 (J.L. Arbuckle, 2001) statistical program to evaluate three models of increasing complexity, to compare how well each fit the data set, and to identify the one that best described the underlying constructs measured by the DAS. Results suggested that the synthesized Three‐Stratum CHC Model provided the most parsimonious representation among the three models tested. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 119–138, 2007.

A current theory of attention deficit/hyperactivity disorder (ADHD) implicates a dysfunction in working memory as a significant factor in ADHD. The Working Memory Indexes of the Wechsler Adult Intelligence Scale--Third Edition (WAIS-III; The Psychological Corporation, 1997a) and the Wechsler Memory Scale--Third Edition (WMS-III; The Psychological Corp -oration, 1997b) were used to evaluate this theory. Seventy adults clinically diagnosed with ADHD (mean age = 25) and who were previously administered the WAIS-III and WMS-III were reviewed to determine the association between working memory and ADHD symptomology. The respondent was asked to estimate the frequency of occurrence of ADHD symptoms by completing the Brown ADD Scales (Brown, 1996). Results indicated no significant relationship between working memory and self-reported symptoms, although the Working Memory Indexes of the WAIS-III and the WMS-III were significantly correlated. Implications for current ADHD theory and suggestions for future research were discussed.

This study investigated the structure of the Differential Ability Scales (DAS; Elliott, 1990a) using confirmatory factor analysis with 130 normal school-aged children. Maximum likelihood estimation, using the six Core subtests, found an extremely good fit with the data and supported the DAS model proposed by Elliott (1990a). In addition, the six Core subtests were found to be strong measures of g, supporting their contribution to the General Conceptual Ability. Replication of Keith's (1990) final model, which included the six Core subtests and three Diagnostic subtests, was also conducted. This model was based on the same theoretical framework against which Keith (1990) tested his models. This theoretical framework was derived from a logical analysis of the nature of the subtests in light of prior research. The present study found a reasonably good fit for the data when the model included both the Core and Diagnostic subtests.

The validity of the Differential Ability Scales (DAS; Elliott, 1990) in predicting attention disorders in school-aged children was examined. The participants were 40 children diagnosed with attention deficit/hyperactivity disorder (ADHD) and 40 normal children between 7 and 12 years of age. Comorbidity was controlled by excluding children with ADHD who had a concurrent DSM-IV diagnosis such as reading disability, learning disability, mood disorder, or behavioral disorder. In addition, groups did not differ significantly by sex, age, racial/ethnic identification, or parental educational level. A stepwise discriminant analysis indicated the DAS correctly classified 72.5% of the total sample when either the Sequential and Quantitative Reasoning subtest or the Recall of Digits subtest was used to predict group membership. In general, the DAS core subtests were found to be good measures of cognitive ability in children classified with ADHD and did not appear to be influenced by attention problems.

To examine the personal adjustment and vocational outcomes of adults with different subtypes of specific learning disabilities. Design: Cluster analysis was used to derive subtypes from a vocational rehabilitation population, and nonparametric tests were used to test hypotheses. Participants: Three hundred sixty-one successfully employed persons were compared with 252 unsuccessfully employed persons. Main Outcome Measures: Rates of secondary psychiatric disorders, type of training, and category of vocational attainment were the outcome measures. Results: Subtype was associated with vocational outcome and training but not with prevalence of secondary psychiatric diagnosis. Conclusions: Subtypes of specific learning disabilities exist in the vocational rehabilitation population and are associated with differences in vocational training, success rates, and occupational placement.Public Law 94-142 was enacted in 1975 to guarantee a free and appropriate education to all school-aged children in the United States irrespective of handicapping condition (Education for All Handicapped Children Act of 1975, 20 USC § 401, as cited in Alexander & Alexander, 1992. Currently, as a recognized disability, specific learning disabilities (SLD) constitute the most common handicapping disorder served in the public schools (U.S. Department of Education, 1994). Much research has been disseminated examining the cognitive, academic,