Prabir Kumar Das Indian Institute of Foreign Trade Kolkata   Chowbagha Road, Ward No 108 Chowbagha Road, Ward No 108 Borough XII, Kolkata 700107 Kolkata, West Bengal 700107 India   pkdas@iift.edu   http://www.iift.edu/           JEL Areas: C : Mathematical and Quantitative Methods M : Business Administration and Business Economics; Marketing; Accounting