Beyond Levels and Growth: Estimating Teacher Value-Added and its Persistence
研究发现，传统水平与增长模型对教师影响持续性的假设若错误，会导致增值估计严重偏差。本文提出一个累积模型，可同时估计教师质量及其持续性，并用北卡罗来纳州数据验证，仅约三分之一的同期教师效应延续至下一年级。
The levels and growth achievement functions make extreme and diametrically opposed assumptions about the rate at which teacher inputs persist. I first show that if these assumptions are incorrect, teacher value-added estimates can be significantly biased. I then develop a tractable, cumulative model of student achievement that allows for the joint estimation of unobserved teacher quality and its persistence. The model can accommodate varying persistence rates, student heterogeneity, and time-varying teacher attributes. I implement the proposed methodology using schooling data from North Carolina, and find that only a third of the contemporaneous teacher effect survives into the next grade.