Identification with Imperfect Instruments
---- Acknowledgements ----
We thank Joel Horowitz, Chuck Manski, Rob Porter, and Elie Tamer as well as seminar participants at Northwestern University, University College London, SITE, University of Paris I, and the University of Toronto for comments. Adam Rosen gratefully acknowledges financial support form the Center for the Study of Industrial Organization, the Eisner Memorial Fellowship at Northwestern University, and the Economic and Social Research Council through the ESRC Centre for Microdata Methods and Practice grant RES-589-28-0001. The authors are solely responsible for any and all errors. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.