1. William H. Abbott Professor of International Business and Economics, Graduate School of Business, University of Chicago, Chicago, Illinois; Research Associate, National Bureau of Economic Research, Cambridge, Massachusetts; and Visiting Scholar, American Enterprise Institute, Washington, D.C.
2. Office of Employment and Unemployment Statistics, Bureau of Labor Statistics, Washington, D.C.
3. Professor of Economics, University of Maryland, College Park, Maryland, and Research Associate, National Bureau of Economic Research, Cambridge, Massachusetts.