1. Yale School of Management, 135 Prospect St., P.O. Box 208200, New Haven, CT 06520-8200 and NBER.
2. Yale School of Management, 135 Prospect St., P.O. Box 208200, New Haven, CT 06520-8200.
3. Yale School of Management, 135 Prospect St., P.O. Box 208200, New Haven, CT and 06520-8200 and NBER.