1. Department of Biostatistics; Yale University; New Haven Connecticut United States of America
2. Department of Statistics; Nanjing University of Finance and Economics; Nanjing Shi Jiangsu Sheng China
3. School of Economics, Wang Yanan Institute for Studies in Economics; Xiamen University; Xiamen Shi Fujian Sheng China
4. Merck Research Laboratories; Rahway New Jersey United States of America