Intelligence and Achievement: A Factor Analytic and Canonical Correlational Study

Abstract

Recent assertions that tests of intelligence and achievement measure identical constructs contradict the current use of such tests to verify discrepancies between ability and achievement in the identification of children who may experience learning disabilities. This situation poses fundamental challenges to many measurement-related practices that concern school psychologists. To address these issues, the present study examined the constructs measured by such tests and the amount of functional overlap between them. Scores on the Wechsler Intelligence Scale for Children-Revised, the Wide Range Achievement Test, and the SRA Achievement Series were collected from 160 children (80 girls, 80 boys), aged 9-12, selected from a small, urban school district in the Midwest. Data initially were submitted to a principal factor analysis with Varimax rotation, which yielded four factors subsequently labelled Verbal Comprehension, Numerical, Written Language, and Performance. Canonical variates were extracted for the purpose of examining redundancy between the intelligence and achievement batteries. These indicated a functional overlap that accounted for 31.0% of the variance of the WISC-R subtests and 47.2% of the variance of the combined WRAT and SRA subtests. Results were interpreted to offer cautious support for current approaches in diagnosis.

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