1. Center of Statistical Research, School of StatisticsSouthwestern University of Finance and EconomicsChengdu China
2. Department of StatisticsCollege of Mathematics, Southwest Jiaotong UniversityChengdu, Sichuan 611756 China
3. The Hong Kong Jockey Club Centre for Suicide Research and Prevention, Department of Social WorkUniversity of Hong KongHong Kong
4. Institute of Public HealthSchool of Medicine, National Yang‐Ming UniversityTaipei Taiwan
5. Department of StatisticsGeorge Washington UniversityWashington, D.C. U.S.A.