1. a Division of Biostatistics and Bioinformatics , National Health Research Institutes , Zhunan Town, Miaoli County, Taiwan
2. b Department of Biostatistics and Bioinformatics , Duke University Medical Center , Durham, North Carolina
3. c Department of Statistics , National Cheng-Kung University , Tainan, Taiwan
4. d CDRH , U.S. Food and Drug Administration , Rockville, Maryland, USA