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Differential Ability Scales
(DAS)
Step-by-step
Analysis

1 Narrow abilities are those reported in
Kevin McGrew & Dawn Flanagan’s 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.
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