Division of Health Policy and Management, School of Public Health, University of California, Berkeley, 50 University Hall, Room 245, Berkeley, CA, 94720, USA. hrod@berkeley.edu. RAND Corporation, Boston, MA, USA. Department of Health Policy and Management, Fielding School of Public Health, University of California, California, Los Angeles, USA. UCLA Center for Health Policy Research, Fielding School of Public Health, University of California, California, Los Angeles, USA. Division of Health Services Management, School of Public Health, University of Maryland, College Park, MD, USA.