1. Department of Health Management and Policy, The University of Michigan School of Public Health, Ann Arbor, Michigan 48109-2029; e-mail,
2. Department of Economics, The University of Michigan School of Literature, Arts and Sciences, Ann Arbor, Michigan 48109-2029; e-mail,
3. Department of Health Services Administration, The University of Pittsburgh Graduate School of Public Health, Pittsburgh, Pennsylvania 15260; e-mail,