Fatma Youssef Institut Supérieur de Gestion Tunis   Institut Supérieur de Gestion 41 Rue de la Liberté Bouchoucha Bardo, Tunis 2000 Tunisia   fatma_you@yahoo.fr             JEL Areas: A2 : Economics Education and Teaching of Economics: General E3 : Prices, Business Fluctuations, and Cycles: General (includes Measurement and Data)