1. Department of Biostatistics, School of Public Health and Key Laboratory of Public Health SafetyFudan University Shanghai 200032 China
2. Collaborative Innovation Center of Social Risks Governance in Health, Fudan University Shanghai 200032 China
3. Department of Epidemiology and BiostatisticsUniversity of South Carolina Columbia SC29208 U.S.A.
4. Department of StatisticsFudan University Shanghai 200433 China
5. Department of Statistics and Actuarial ScienceThe University of Hong Kong Hong Kong