The Effect of the Prior Teacher on Value-Added

We show that teachers' value-added (‘VA’) depend on the VA of the teachers that preceded them. To do so, we use administrative data from North Carolina and find that a one-standard deviation increase in last grade's mean teacher VA causes a 0.08σ decrease in teacher VA. Controlling for prior teacher assignment eliminates this bias. Under a benchmark policy that releases teachers in the bottom five percent of the VA distribution, thirty-two percent of teachers are incorrectly released using traditional techniques. Our results highlight the importance of incorporating dynamic features of education production into the estimation of teacher quality.