1. a StatPlus, Inc. , Heston Hall, Suite 206, Yardley-Langhorne Road, Yardley, PA, 19067, U.S.A.
2. b Department of Statistics , University of Wisconsin , 1210 W. Dayton Street, Madison, WI, 53706, U.S.A.
3. c Pharmaceutical Research Institute, National Defense Medical Center , Taiwan, ROC