1. University of Texas Austin, McCombs School of Business, University of Texas at Austin, 2110 Speedway, B6600, Austin, TX 78712 (e-mail: )
2. London School of Economics, 32 Lincoln's Inn Fields, 3.09, London WC2A 2AE, United Kingdom, Innovations for Poverty Action, and Jameel Poverty Action Lab (e-mail: )
3. Sloan School of Management, Massachusetts Institute of Technology, E62-638, 100 Main Street, Cambridge MA 02139, NBER, and ideas42 ()