Institution: | a Canada Research Chair at University of British Columbia and NBER, Department of Economics, University of British Columbia, Room 997-1873 East Mall, Vancouver, BC, Canada V6T 1Z1 b Université de Toulouse (GREMAQ, IDEI, Institut Universitaire de France and CEPR), Aile Jean-Jacques Laffont, Université des Sciences Sociales, 21 Allée de Brienne, F-31042 Toulouse, France |