Differential Teacher Attrition : Do High-Ability Teachers Exit at Higher Rates?

Prior evidence of differential teacher attrition is conflicting. Studies that use proxies such as certification scores, SAT or ACT scores, or the selectivity of the teacher's undergraduate institution tend to find that attrition is highest among high-ability teachers. In contrast, many studies that use value-added measures find that teachers with high value-added scores have lower attrition rates. This work presents new evidence on the nature of differential teacher attrition in Texas and attempts to reconcile these conflicting results. Using teacher certification scores as a proxy for teacher ability, this work finds that differential attrition varies with teacher experience. Among new teachers, attrition is concentrated among the least able, but after the first year, attrition rates are highest among high-ability teachers. These findings could explain why many studies that focus on early-career attrition tend to find that low-ability teachers have higher attrition rates. Other conflicting results may be explained by how studies measure teacher ability. Many value-added studies may confound teacher ability with experience, effort, and unobserved school attributes making it appear, perhaps incorrectly, as though the most able teachers have lower attrition rates. Prior studies that carefully measure teacher ability over longer career trajectories tend to corroborate the alarming conclusion that public schools are losing their most able teachers