German Almanza Department of Social Sciences, Autonomous University of Juarez City   ICSA Av. Universidad y Av. Heroico Colegio Militar S/N Zona Chamizal Ciudad Juarez, Chihuahua C.P. 32300 Mexico   ralmanza@uacj.mx             JEL Areas: C6 : Mathematical Methods and Programming: General O4 : Economic Growth and Aggregate Productivity: General