1. School of Statistics and Mathematics, Shanghai Lixin University of Accounting and Finance, Shanghai, China;
2. College of Science, North China University of Technology, Beijing, China;
3. Center for Applied Statistics, School of Statistics, Renmin University of China, Beijing, China;
4. School of Statistics and Information, Xinjiang University of Finance and Economics, Urumqi, China;
5. School of Statistics, Lanzhou University of Finance and Economics, Lanzhou, China