1. Institute for Social Research, University of Michigan, 426 Thompson Street, Ann Arbor, MI 48106, USA
2. Urban Institute, Washington, DC, USA
3. University of Michigan, Ann Arbor, MI, USA
4. Consultant, Granville, OH, USA
5. University of Southern California, Los Angeles, CA, USA
6. National Center for Health Statistics, Hyattsville, MD, USA
7. Consultant, Columbia, MD, USA
8. RAND, Arlington, VA, USA
9. University of California Los Angeles, Los Angeles, CA, USA