William B Weeks1,2,3, Bruno Ventelou3, Zeynep Or4. 1. The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth College, Hanover, NH, USA. 2. The Geisel School of Medicine, Hanover, NH, USA. 3. Aix-Marseille School of Economics (CNRS & EHESS), Aix-Marseille University, Marseille, France. 4. Institut de recherché et documentation en économie de la santé, Paris, France.