1. Department of Statistics College of Economics, Jinan University, Guangzhou, Guangdong, P. R. China
2. School of Statistics and Management, Shanghai University of Finance and Economics, Shanghai, P. R. China
3. College of Economics, Jinan University, Guangzhou, Guangdong, P. R. China
4. Department of Human Resources, Jinan University, Guangzhou, Guangdong, P. R. China