Volume 18, Issue 1 (1989)
Errors in Decision-Making: A comparison of School Psychologists' Interpretation of Grade Equivalents, Percentiles, and Deviation IQs
E. Scott Huebner
ABSTRACT: Fifty-six school psychologists reviewed a hypothetical case study designed to investigate their interpretations of different norm-referenced test scores (grade equivalents vs. percentiles vs. deviation IQs). Although the scores were statistically equivalent (the same position in the score distribution), school psychologists were more likely to recommend special education programs for normal students when percentile scores were used. The results suggest that school psychologists need to become more familiar with the properties of percentile scores. Accurate interpretation of norm-referenced test scores is a prerequisite to appropriate psychoeducational decision-making.
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