Multiple IQ-Achievement Comparisons: Effects on Severe Discrepancy Determination
Increased Type I error resulting from multiple IQ-achievement comparisons may inflate learning disability identification rates for discrepancy models. The magnitude of such inflation was investigated with 87 referred students given the WISC-R and Woodcock-Johnson (R) Tests of Achievement. Five IQ-achievement comparisons were made for each student. Correction for multiple comparisons significantly decreased the number of students and achievement areas found to demonstrate significant IQ-achievement differences. However, less dramatic decreases were found for students and achievement areas determined to show discrepancies. It was concluded that the magnitude of inflation is a function of number of comparisons, degree of correction for multiple comparisons, and discrepancy model used.