Severe Discrepancy Models: Which Best Explains School Identification Practices for Learning Disabilities?

This study examined which of three types of severe discrepancy approaches—intraindividual achievement discrepancy, absolute achievement discrepancy, or relative achievement discrepancy—best accounted for students' identification as learning disabled (LD). Participants were 48 fourth-grade, school-identified LD students from a high-achieving and a low-achieving school district in Minnesota. Students were tested with a short form of the WISC-III and two measures of reading, and the resulting discrepancies were matched to students' school LD classification. Results showed that the best explanation for school-based LD identification practices was a relative achievement discrepancy, with between 85–95% of LD students in both districts identified accurately. The state-mandated ability-achievement discrepancy accounted for only 60% of LD students. Implications of these findings for LD identification practice based on an ecological perspective are discussed.