Testing the Unconfoundedness Assumption via Inverse Probability Weighted Estimators of (L)ATT
2013/02/19
研討會日期 : 2013-02-19
時間 : 14:30
主講人 : Professor Yu-Chin Hsu
地點 : Conference Room B110
演講者簡介 : Yu-Chin Hsu received his Ph.D. in Economics from University of Texas at Austin in 2010. He is currently serving as Assistant Research Fellow of Institute of Economics, Academia Sinica. His research field is in econometric theory.
演講摘要 : We propose inverse probability weighted estimators for the local average treatment effect (LATE) and the local average treatment effect for the treated (LATT) under instrumental variable assumptions with covariates. We show that these estimators are asymptotically normal and efficient. When the (binary) instrument satisfies one-sided non-compliance, we propose a Durbin-Wu-Hausman-type test of whether treatment assignment is unconfounded conditional on some observables. The test is based on the fact that under one-sided non-compliance LATT coincides with the average treatment effect for the treated (ATT). We conduct Monte Carlo simulations to demonstrate, among other things, that part of the theoretical efficiency gain afforded by unconfoundedness in estimating ATT survives pre-testing. We illustrate the practical implementation of the test on data from training programs administered under the Job Training Partnership Act.
