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Confirmatory factor analyses of the WAIS-III standardization data
L Charles Ward1, Joseph J Ryan, Bradley N Axelrod
1Veterans Affairs Medical Ctr.
Psychological Assessment
|October 6, 2000
Summary
Confirmatory factor analyses of the Wechsler Adult Intelligence Scale-Third Edition suggest a two-factor model with Verbal Comprehension offers a parsimonious and effective structure for intelligence assessment.
Area of Science:
- Psychometrics
- Cognitive Psychology
- Educational Measurement
Background:
- The Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) is a widely used measure of adult intelligence.
- Understanding the underlying factor structure of intelligence tests is crucial for accurate interpretation.
Purpose of the Study:
- To compare various factor models (1-4 factors) for the WAIS-III using confirmatory factor analysis.
- To evaluate the fit and parsimony of different factor structures, including traditional Verbal/Performance and alternative models.
Main Methods:
- Confirmatory factor analyses were performed on the standardization data of the WAIS-III.
- Six models with varying numbers of factors (1-4) were compared for 11- and 13-subtest versions.
Main Results:
- Three-factor models generally provided a better fit than two-factor models.
- A two-factor model emphasizing Verbal Comprehension (Vocabulary, Similarities, Information, Comprehension) demonstrated comparable or superior performance to the traditional Verbal/Performance split.
- Adding a fourth factor for processing speed subtests offered minimal advantage over three-factor models with correlated errors.
Conclusions:
- The two-factor Verbal Comprehension model presents a viable and parsimonious alternative to the traditional WAIS-III structure.
- Factor analysis supports nuanced interpretations of adult intelligence beyond simple Verbal/Performance distinctions.