Volume 28, Issue 2 (1999)
The Absence of Structural Fidelity Precludes Construct Validity: Rejoinder to Naglieri on What the Cognitive Assessment System Does and Does Not Measure
Timothy Z. Keith, John H. Kranzler
Abstract: In this rejoinder,we show that Naglieri’s(1999a)commentary thoroughly fails to refute the results of Kranzler and Keith’s (1999) research on the factor structure of the Cognitive Assessment System(CAS). We begin by reviewing contemporary theory of construct validity with an emphasis on the role of factor analysis in “strong” validation programs. Next, we respond to the main theoretical and empirical issues raised by Naglieri(1999a)in his commentary regarding the results of our confirmatory factor analyses of the standardization data of the CAS. Finally, we critique the external evidence of validity he presented and emphasize the need for further research on the factor structure of the CAS.We also express concern with Naglieri’s continued selective and misleading use of quotations.In sum,our research indicates that the CAS lacks structural fidelity, a necessary but not sufficient condition for construct validity. An absence of structural fidelity indicates that the scaled scores derived from the CAS do not correspond to the underlying theory upon which the test is based. The external evidence of validity presented by Naglieri in his rejoinder is therefore meaningless. School psychologists and other practitioners are advised to interpret the CAS with caution, if at all.
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