1. School of Mathematics and Statistics, Chongqing Technology and Business University, Chongqing, People's Republic of China
2. School of Mathematical Sciences, University of Electronic Science and Technology of China, Chengdu, People's Republic of China
3. Chongqing Key Laboratory of Social Economy and Applied Statistics, Chongqing, People's Republic of China
4. School of Business, East China University of Science and Technology, Shanghai, People's Republic of China