Evaluating Marginal Policy Changes and the Average Effect of Treatment for Individuals at the Margin

This research was supported by NIH R01-HD32058-3, NSF SES-0832845, NSF SES-024158, NSF SES-05-51089, ESRC RES-000-22-2542, the Geary Institute at University College Dublin, the Leverhulme Trust, and ESRC (NIH R01-HD054702) through the funding of the Centre for Microdata Methods and Practice. The research was conducted in part while Edward Vytlacil was a Visiting Professor at Hitotsubashi University. We thank the editor, two anonymous referees, Hidehiko Ichimura, Richard Robb, Daniel Schmierer, and Azeem Shaikh for very helpful comments. We would like to thank Erica Blom and Sukjin Han for research assistance. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.