Giam Quang Do Associate Professor   Faculty of Accounting and Business Management Vietnam National University of Agriculture Trau Quy Gia Lam, Hanoi 100000 Vietnam   dqgiam@vnua.edu.vn   http://eng.vnua.edu.vn/           JEL Areas: C1 : Econometric and Statistical Methods: General C3 : Multiple or Simultaneous Equation Models: General