Estimating the Effect of Job-Training Programs, Using Longitudinal Data: Ashenfelter's Findings Reconsidered
指出常用于评估职业培训项目的自回归收入模型会严重偏误估计项目效果的大小和时间模式，并用更合适的模型重新分析Ashenfelter的数据，发现其估计的培训效应衰减源于模型的时间变化偏误。
This paper is an examination of how autoregressive earnings models commonly used to evaluate job-training programs can produce badly biased estimates of both the magnitude and the temporal pattern of program impacts. Ashenfelter's results are used to illustrate this point, and a new, more appropriate model is used to reanalyze his data. Of particular importance is the finding that the decay in Ashenfelter's estimated training effect for men was produced by a time-varying bias in his model.