Factor Structure of the Differential Ability Scales–Second Edition Core Subtests: Standardization Sample Confirmatory Factor Analyses

The present study examined the factor structure of the Differential Ability Scales–Second Edition (DAS-II) core subtests from the standardization sample via confirmatory factor analysis (CFA) using methods (bifactor modeling and variance partitioning) and procedures (robust model estimation due to nonnormal subtest score distributions) recommended but not included in the DAS-II Introductory and Technical Handbook. CFAs were conducted with the three DAS-II standardization sample age groups (lower early years [age = 2:6–3:5 years], upper early years [age = 3:6–6:11 years], school age [7:0–17:11 years]) using standardization sample raw data provided by NCS Pearson, Inc. Although most DAS-II core subtests were properly associated with the theoretically proposed group factors, both the higher order and bifactor models indicated that the g factor accounted for large portions of total and common variance, whereas the group factors (Verbal, Nonverbal, Spatial) accounted for small portions of total and common variance. The DAS-II core battery provides strong measurement of general intelligence, and clinical interpretation should be primarily, if not exclusively, at that level.

Investigating the Theoretical Structure of the Differential Ability Scales—Second Edition Through Hierarchical Exploratory Factor Analysis

When the Differential Ability Scales–Second Edition (DAS-II) was developed, the instrument’s content, structure, and theoretical orientation were amended. Despite these changes, the Technical Handbook did not report results from exploratory factor analytic investigations, and confirmatory factor analyses were implemented using selected subtests across the normative age groups from the total battery. To address these omissions, the present study investigated the theoretical structure of the DAS-II using principal axis factoring followed by the Schmid–Leiman procedure with participants from the 5- to 8-year-old age range to determine the degree to which the DAS-II theoretical structure proposed in the Technical Handbook could be replicated. Unlike other age ranges investigated where at most 14 subtests were administered, the entire DAS-II battery was normed on participants aged 5 to 8 years, making it well suited to test the full instrument’s alignment with theory. Results suggested a six-factor solution that was essentially consistent with the Cattell–Horn–Carroll (CHC)-based theoretical structure suggested by the test publisher and simple structure was attained. The only exception involved two subtests (Picture Similarities and Early Number Concepts) that did not saliently load on a group factor. Implications for clinical practice are discussed.

Testing for Construct Bias in the Differential Ability Scales, Second Edition: A Comparison Among African American, Asian, Hispanic, and Caucasian Children

Individually administered intelligence measures are commonly used in diagnostic work, but there is a continuing need for research investigating possible test bias among these measures. One current intelligence measure, the Differential Ability Scales, Second Edition (DAS-II), is a test with growing popularity. The issue of test bias, however, has not been thoroughly investigated with the DAS-II. The current study investigated whether the DAS-II demonstrates systematic construct bias when used with children from three racial and ethnic groups—African American, Asian, and Hispanic—when compared to non-Hispanic Caucasian children. Multi-group confirmatory factor analyses with data from the DAS-II standardization sample were used to assess whether the constructs and measurement of constructs were invariant across groups. Results indicate cross-group internal structure validity in the DAS-II, and thus a lack of construct bias. Minor differences were found, but these differences do not affect the calculation of composite scores on the DAS-II and thus would not result in unfair scoring for the groups involved. Results of this study support the appropriateness of the DAS-II for clinical use with these racial and ethnic groups.