We study how the introduction of a rigorous teacher evaluation system in a large urban school district affects the quality composition of teacher turnovers. With the implementation of the new system, we document increased turnover among the least effective teachers and decreased turnover among the most effective teachers, relative to teachers in the middle of the distribution. Our findings demonstrate that the alignment between personnel decisions and teacher effectiveness can be improved through targeted personnel policies. However, the change in the composition of exiters brought on by the policy we study is too small to meaningfully impact student achievement.

We compare teacher preparation programs in Missouri based on the effectiveness of their graduates in the classroom. The differences in effectiveness between teachers from different preparation programs are much smaller than has been suggested in previous work. In fact, virtually all of the variation in teacher effectiveness comes from within-program differences between teachers. Prior research has overstated differences in teacher performance across preparation programs by failing to properly account for teacher sampling.