Exit rates from Limited English Proficiency (LEP) for students who enter the Wake County Public School System (WCPSS) as LEP students vary by when students enter WCPSS (based on students entering in kindergarten, grade 6 or 7, or grade 9). Based on our 2008-09 cohorts, students entering in grades 6 or 7 were most likely to exit LEP status after…

Background: Cluster-randomized experiments that assign intact groups such as schools or school districts to treatment conditions are increasingly common in educational research. Such experiments are inherently multilevel designs whose sensitivity (statistical power and precision of estimates) depends on the variance decomposition across levels.…