Prevalence Rates of Students Identified for Special Education and Their Interstate Variability: A Longitudinal Approach

We investigated the variability across states in the prevalence of learning disabilities (LD) as reported by the U. S. Department of Education’s Office of Special Education Programs (OSEP). This expanded upon the work of Hallahan and colleagues on interstate prevalence rate variability of special education disability categories by focusing on a longitudinal analysis. Furthermore, we examined the effect of response to intervention (RTI) on the change in identification of LD more than 12 years from Fall 2000 through Fall 2011 for ages 6 to 17 years. We used the coefficient of variation (CV) to compare variability of prevalence rates and applied a piecewise regression to examine the effect of RTI. The results are consistent with Hallahan and colleagues’ previous findings—LD continues to demonstrate the least prevalence rate variability across states of all disability categories. LD prevalence variability is almost as minimal as that of some naturally occurring and medically diagnosed conditions (e.g., diabetes, asthma). We discuss these results within the context of changing LD identification methods, such as RTI, and decreasing prevalence of LD, suggesting possible reasons for potential changes in both prevalence and its interstate variability in the future.