Teacher Value-Added and Economic Agency

Teacher value-added is not a technological ‘primitive.’ Instead, it increases within-teacher when accountability incentives are strengthened, as we show. This evidence motivates a framework in which teacher value-added depends on two unobserved inputs to education production: teacher ability and incentive-varying teacher effort. We present a strategy to identify these two inputs and their distinct effects on test scores for the first time, using exogenous incentive policy variation and rich longitudinal data from North Carolina. The estimates indicate that both the ability component of teacher value-added and teacher effort raise current and future scores. We also find that effort responds systematically to incentives, underlining the agency of the teaching force as an important factor in education production. To explore the policy implications of this economic agency, we then use our estimates to compare the cost effectiveness of incentive-oriented education reforms with policies that target teacher ability. Incentive reforms come out ahead in a variety of plausible cases, given their potential to influence all teachers rather than a subset.