1. Otto Eckstein Professor of Applied Economics, Harvard University, Cambridge, Massachusetts; Research Associate, National Bureau of Economic Research, Cambridge, Massachusetts.
2. Dwight D. Eisenhower Professor of International Affairs at the Woodrow Wilson School of Public and International Affairs and Professor of Economics and International Affairs, both at Princeton University, Princeton, New Jersey; Research Associate, National Bureau of Economic Research, Cambridge, Massachusetts.
3. Assistant Professor of Economics and Public Policy, Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey; Faculty Research Fellow, National Bureau of Economic Research, Cambridge, Massachusetts.