First Author:   Arouri Mohamed el hédi LEO - Université d''Orléans & EDHEC Mohamed.arouri@univ-orleans.fr         Second Author: Jamel Jouini GREQAM, and FSEGN, Tunisie Jamel.Jouini@fsegn.rnu.tn   Campus Universiatire Mrezgua, Campus Universiatire Mrezgua Nabeul, 8000, Tunisie   +216 72 232 205(Phone) +216 72 232 318(Fax)