Students are non-randomly assigned, or sorted, into classrooms in various ways across and within schools. In this study, we use longitudinal data sets from three districts to investigate a metric for the characterization of sorting at the school level. We analyze whether non-random student assignment is associated with value-added estimates for…

The federal government's Race to the Top competition has promoted the adoption of test-based performance measures as a component of teacher evaluations throughout many states, but the validity of these measures has been controversial among researchers and widely contested by teachers' unions. A key concern is the extent to which nonrandom sorting…