1. a Health Care Systems Department , The Wharton School, University of Pennsylvania , 3641 Locust Walk, Philadelphia, PA 19104‐6218, USA Phone: Fax: E-mail:
2. b Department of Health Policy & Management , Emory University’s Rollins School of Public Health , 1518 Clifton Road NE., Atlanta, GA 30322, USA Phone: Fax: E-mail:
3. c Health Care Systems Department , The Wharton School, University of Pennsylvania , 3641 Locust Walk., Philadelphia, PA 19104‐6218, USA Phone: Fax: E-mail: