1. Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544.
2. Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544; National Bureau of Economic Research.
3. Department of Management, McCombs School of Business, University of Texas, Austin, TX 78712.
4. Institute for Social Research, University of Michigan, Ann Arbor, MI 48106.
5. Department of Psychiatry and Behavioral Science, School of Medicine, Stony Brook University, Stony Brook, NY 11794.