1. US Census Bureau, 4600 Silver Hill Road, Room 8H120, Washington, DC 20233, and Cornell University (email: )
2. Department of Economics, University of Georgia, Amos Hall B408, Athens, GA 30602, and US Census Bureau (email: )
3. Labor Dynamics Institute, Cornell University, 352 East Ives Hall, Ithaca, NY 14853, and US Census Bureau (email: )