Sivashankar Sivakumar University of Jaffna   Department of Agricultural Economics Faculty of Agriculture University of Jaffna Kilinochchi, Northern 44000 Sri Lanka   ssivashankar@univ.jfn.ac.lk   https://sites.google.com/univ.jfn.ac.lk/sivashankar           JEL Areas: D0 : Microeconomics: General C4 : Econometric and Statistical Methods: Special Topics