1. Guanghua School of Management, Peking University, Beijing, People’s Republic of China
2. Center for Statistical Science, Peking University, Beijing, People’s Republic of China
3. Yuanpei College, Peking University, Beijing, People’s Republic of China
4. Center for Data Science, Peking University, Beijing, People’s Republic of China
5. Department of Statistics, Iowa State University, Ames, IA, USA
6. School of Mathematical Science, Peking University, Beijing, People’s Republic of China