First Author:   Olivier Gergaud BEM - Bordeaux Management School and University of Reims olivier.gergaud@bem.edu   680 cours de la libération Talence, 33405 Cedex, France   + 33 (0) 26 08 22 35(Phone) + 33 (0) 26 08 22 35(Fax) http://olivier.gergaud.free.fr Second Author: Victor Ginsburgh ECARES, Brussels and CORE, Louvain-la-Neuve vginsbur@ulb.ac.be   ECARES, Université Libre de Bruxelles, 50, Avenue Franklin Roosevelt, C.P. 114/04 Brussels, 1050, Belgium       Third Author: Florine Livat BEM - Bordeaux Management School florine.livat@bem.edu         http://