It is a mistake to equate the setting in which a student is educated (that is, the general-education classroom) with the actual progress a student is making. Such an assumption ignores the fact that students are found eligible for special-education services precisely because they are failing to progress in general education. Placement data may suggest that SWDs are being exposed to the general-education curriculum, but achievement data suggest that they are not actually learning the curriculum: SWDs placed in general-education classrooms continue to lag dramatically behind their peers. A recent meta-analysis that I conducted with my colleagues Doug Fuchs and Joe Wehby estimated that SWDs score about 1.2 standard deviations below their non-disabled peers in reading, a gap that translates to more than three years of academic growth. Achievement gaps between SWDs and their peers are similarly large in math. Though federal laws stress the importance of educating SWDs in the regular classroom, there is no good evidence that placement there improves the outcomes of these students.
More-recent work also finds that SWDs educated in general-education settings have better outcomes. Roddy Theobald and colleagues observed that high-school students with disabilities in Washington State who spent more time in general-education settings had higher reading scores than their peers who had less time in such settings, even after taking into account differences in prior achievement and a wide range of student characteristics. They were also more likely to graduate on time and enroll in college than students educated in more-restrictive settings. Laura Schifter has reported similar results regarding graduation for students in Massachusetts: SWDs educated in general-education classrooms have higher probabilities of graduating than their peers who were educated in more-isolated settings. These recent studies and others have led many to conclude that inclusion benefits SWDs.
Unfortunately, this determination ignores a major limitation of the current research base: the failure to account for selection bias. Students with higher academic abilities or fewer behavioral challenges are more likely to be placed in inclusive settings, while their peers who may have the same disability label but greater learning or behavioral needs are placed in special-education settings. The consistent finding that SWDs have better outcomes when educated in general-education settings likely reflects this bias. Even in studies that account for students’ prior levels of academic achievement, the researchers may not capture all the aspects of a student, such as his behavior, that can influence both the setting in which he is placed and his future outcomes. A student’s educational placement is an IEP team decision and may be based on a host of factors not included in the administrative data sets to which researchers typically have access. This makes estimating the true causal effect of inclusion on student outcomes nearly impossible.