Despite their widespread use, controversy remains about how to best interpret norm-referenced tests of cognitive ability. Due to the fact that contemporary cognitive measures appraise performance at multiple levels (e.g., subtest, factor, full-scale), a multitude of inferences about individual functioning are possible. Because school psychologists primarily utilize intelligence tests for predicting achievement outcomes, the cognitive variables that provide the most optimal weighting for prediction are of greatest importance. This study examined the predictive validity of the Cattell-Horn-Carroll (CHC) factor structure from the Woodcock-Johnson III Tests of Cognitive Abilities (WJ-COG; Woodcock, McGrew, & Mather, 2011c). Specifically, the incremental achievement variance accounted for by the CHC broad factors, after controlling for the effects of the General Intellectual Ability (GIA) composite, was assessed across reading, mathematics, writing, and oral language variables from the Woodcock-Johnson III Tests of Achievement (WJ-ACH; Woodcock, McGrew, & Mather, 2001b). Hierarchical regression was used to assess predictive relationships between the cognitive-achievement variables on the Woodcock-Johnson III assessment battery (WJ-III; Woodcock, McGrew, & Mather, 2001a). This study utilized archived standard score data from individuals (N = 4,722) who participated in the original WJ-III standardization project. Results showed that the GIA accounted for the largest portions of achievement for all but one of the regression models that were assessed. Across the models, the GIA variance coefficients represented moderate to large effects whereas the CHC factors accounted for non-significant incremental effects in most of the models. Nevertheless, the WJ-COG factor scores did account for meaningful portions of achievement variance in several situations: (a) in predicting oral expression scores; (b) in the presence of significant inter-factor variability; and (c) when the effects of Spearman's law of diminishing returns (SLODR) was accounted for in reading, mathematics, and written language regression models. Additionally, the chi-square goodness of fit test was utilized to assess model invariance across several moderating variables. Results suggest that incremental validity is not a unitary construct and is not invariant across samples on the WJ-COG. Additionally, simultaneous interpretation of both the GIA and CHC factor scores on the WJ-COG may be useful within specific clinical contexts.
|Advisor:||Busse, Randy T.|
|Commitee:||Brady, John T., Kennedy, Kelly S., Olvera, Pedro|
|Department:||College of Education Studies|
|School Location:||United States -- California|
|Source:||DAI-A 75/09(E), Dissertation Abstracts International|
|Subjects:||Educational tests & measurements, Educational psychology, Quantitative psychology|
|Keywords:||Cattell-Horn-Carroll factor, Intelligence quotient, Interpretation, Validity|
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