1. Department of Health Policy and Management; Seoul National University College of Medicine, and Institute of Health Policy and Management, Seoul National University Medical Research Center; Seoul Korea
2. Department of Health Management and Policy & Department of Economics; University of Michigan and NBER; Ann Arbor MI USA
3. Department of Health Policy and Management; University of North Carolina at Chapel Hill; Chapel Hill NC USA
4. Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center, Department of Medicine; Duke University Medical Center; Durham NC USA