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Differential Ability Scales (DAS)

Step-by-step Analysis

1 Narrow abilities are those reported in Kevin McGrew & Dawn Flanaganís The Intelligence Test Desk Reference (ITDR):Gf-Gc Cross-Battery Assessment (Allyn & Bacon, 1998)

2 Shared abilities are those provided by Elliott (1990): Nonverbal Problem Solving (Mat, SQR, PCon, PSim); Verbal Conceptualization (WDef, Sim, VComp, NVoc); Formulation and Testing of Hypotheses (Sim, Mat, SQR, PCon, PSim); Spatial Visualization and Orientation (RDes, PCon, Copy, Enc, MLLF); Visual Discrimination of Figures or Designs (Mat, SQR, RDes, RPic, PSim, Copy, MLLF); Verbal Comprehension (WDef, Sim, VComp, Enc); Verbal Expression (WDef, Sim, RDig, RObj, NVoc, Enc); Verbal Information Retrieval - Long-term Memory (WDef, Sim, NVoc, Enc); Knowledge of Quantitative Concepts (SQR (b), SIP); Short-term Memory - general (RDes, RDig, RObj, RPic); Visual Short-term Memory (RDes, RObj, RPic);Verbal Short-term Memory (RDig, SIP); Speed of Information Processing (PCon, SIP); Visual/holistic Information Processing (Mat, RDes, PCon, RObj, RPic, PSim, Copy, MLLF); Verbal/Sequential Information Processing (WDef, Sim, SQR, RDig, SIP, VComp, NVoc, Enc).

Step One: Evaluate the GCA

The General Conceptual Ability score is the most reliable and valid score usually obtained on the DAS. It is considered to be an excellent measure of general cognitive ability (g) as well as being the best predictor of overall academic achievement for both children with disabilities and children without disabilities (Youngstrom, Kogos, & Glutting, 1999).

Interpreters must determine whether the GCA score represents the best summary of overall intellectual ability. Does the GCA represent a clinically meaningful measure of the individual's abilities or would reporting and interpreting the various constructs of the DAS provide a more useful explanation of abilities? If the amount of "scatter" within and between the clusters that make up the GCA is insignificant and not unusual compared to the scatter seen in the DAS norming sample, then the GCA score probably summarizes most of the useful information about the student available from that administration of the DAS. If, however, the three cluster scores that combine to create the overall GCA score deviate significantly and unusually from the GCA, more interpretation seems warranted.


Step Two