1. School of Finance and Economics, Jiangsu University, Zhenjiang, P.R. China
2. Institute of Applied Systems Analysis (IASA), School of Mathematics, Jiangsu University, Zhenjiang, P.R. China
3. Department of Statistics and Actuarial Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
4. Department of Public Health, Catholic University of Ghana, Fiapre-Sunyani, Ghana