1. Department of Mathematics and Statistics, Bar Ilan University, Ramat Gan 52900, Israel
2. Biometry Research Group, Division of Cancer Prevention, National Cancer Institute, MSC 7354, Bethesda, Maryland 20892‐7354, U.S.A.
3. Department of Statistics, Texas A&M University, College Station, Texas 77843‐3143, U.S.A.