Direct and indirect effects based on difference-in-differences with an application to political preferences following the Vietnam draft lottery
2016/06/07
研討會日期 : 2016-06-07
時間 : 14:30
主講人 : Professor Martin Huber
主持人 : Professor Yu-Chin Hsu
地點 : Conference Room C103
演講者簡介 : Professor Huber received his Ph.D. in Economics and Finance at University of St. Gallen, Switzerland in 2010. He is currently a Professor at University of Fribourg. His research fields are Policy/treatment effect evaluation in labor, health, and education economics, semi- and nonparametric microeconometric methods for causal inference.
演講摘要 : This paper proposes a difference-in-differences approach for disentangling the direct causal effect of a treatment on an outcome of interest as well as its indirect effect operating through a binary intermediate variable -or mediator- within strata defined upon how the mediator reacts to the treatment. We show under which assumptions the direct effects on the always and never takers, whose mediator is not affected by the treatment, as well as the direct and indirect effects on the compliers, whose mediator reacts on the treatment, are identified. We also provide a simulation study to convey the intuition of our results and an empirical application based on the Vietnam draft lottery. The results suggest that a high draft risk due to the lottery leads to a relative increase in the support for the Republican Party and that this increase was mostly driven by those who complied with the lottery outcome, i.e. were induced to serve in the military.
