[1] Ctr Econometr & Appl Res, Ibadan, Nigeria
[2] Univ Econ Ho Chi Minh City, Inst Business Res, Ho Chi Minh City, Vietnam
[3] Univ Ibadan, Dept Stat, Ibadan, Oyo, Nigeria
[4] Univ Econ Ho Chi Minh City, Inst Business Res & CFVG Ho Chi Minh City, Ho Chi Minh City, Vietnam