1. School of Economics and the Wang Yanan Institute for Studies in Economics, Xiamen University, Xiamen, China
2. School of Statistics and Mathematics, Central University of Finance and Economics, Beijing, China
3. Department of Biostatistics, School of Public Health, University of Texas at Houston, Houston, TX, USA
4. College of Mathematics and Statistics, Institute of Statistical Sciences, Shenzhen University, Shenzhen-Hong Kong Joint Research Center for Applied Statistical Sciences, Shenzhen, China