First Author:   Mohamed Mehdi Jelassi Department of Quantitative Methods & LEFA, IHEC Carthage, Carthage University mehdi.jelassi@gmail.com   Department of quantitative methods, IHEC Carthage Tunis, 2016, Tunisia       Second Author: Ezzeddine Delhoumi Department of Quantitative Methods & LEFA, IHEC Carthage, Carthage University ezd.del@gmail.com   Tunis, 2016, Tunisia