1. Department of Statistics, College of Economics, Jinan University, Guangzhou, GD, China
2. International Institute of Finance/Department of Statistics and Finance, School of Management, University of Science and Technology of China, Hefei, AH, China
3. Department of Statistical Science, School of Mathematics, Sun Yat-Sen University, Guangzhou, GD, China
4. Department of Biostatistics Yale University School of Public Health, New Haven, CT