1. Department of Political Science, Stanford University, Stanford, CA 94305-6044, USA.
2. Immigration Policy Lab, Stanford University, Stanford, CA 94305-6044, USA and University of Zurich, 8050 Zurich, Switzerland.
3. Graduate School of Business, Stanford University, Stanford, CA 94305-6044, USA.
4. Department of Government, London School of Economics and Political Science, London WC2A 2AE, UK.