Accuracy in Analysis of Discrepancy Scores: A Nationwide Study of School Psychologists

Abstract

This study investigated whether psychologists possess the psychometric knowledge necessary to evaluate discrepancies within an individual's test performance with sufficient accuracy to ensure reliable decision making. Two-thirds of a randomly drawn nationwide sample of nationally certified school psychologists responded to a questionnaire that asked them to evaluate four sets of achievement-ability test scores, rate the usefulness of various test measures for different purposes, and provide information on how achievement-ability discrepancies, a criterion for learning disability (LD) classification, were being identified in their settings. Only 8.7% of 287 respondents were able to correctly evaluate whether four sets of ability-achievement scores reflected chance measurement differences or reliable, non-chance differences. Increased accuracy was associated with working in a state recommending regression analysis and providing simplified operational procedures, in the form of tables, for evaluating test score discrepancies.