1. Department of Mathematics, Harbin Institute of Technology, Harbin, P. R. China
2. Division of Biostatistics, Office of Surveillance and Biometrics, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA
3. Department of Biostatistics, St Jude Children’s Research Hospital, Memphis, Tennessee, USA
4. Medical Affairs, GE Healthcare, Milwaukee, Wisconsin, USA