Do Value-Added Estimates Add Value? Accounting for Learning Dynamics
利用巴基斯坦公立和私立学校数据，通过动态面板方法处理学习持续性、未观测异质性和测量误差，发现仅五分之一到一半的学习在年级间持续，且私立学校每年提高平均成绩0.25个标准差。
This paper illustrates the central role of persistence in estimating and interpreting value-added models of learning. Using data from Pakistani public and private schools, we apply dynamic panel methods that address three key empirical challenges: imperfect persistence, unobserved heterogeneity, and measurement error. Our estimates suggest that only one-fifth to one-half of learning persists between grades and that private schools increase average achievement by 0.25 standard deviations each year. In contrast, value-added models that assume perfect persistence yield severely downward estimates of the private school effect. Models that ignore unobserved heterogeneity or measurement error produce biased estimates of persistence.