1. Key Lab of Statistical Modeling and Data Analysis of Yunnan Province Yunnan University Kunming 650091 Yunnan People's Republic of China
2. Department of Mathematical and Statistical Sciences University of Alberta Edmonton Alberta Canada
3. Department of Statistics Jiangsu University of Technology Changzhou 213001 Jiangsu People's Republic of China
4. Zhongtai Securities Institute for Financial Studies Shandong University Jinan Shandong China