1. Institute of Statistics; Ulm University; Ulm Germany
2. Clinical Trials Unit; Medical Center Freiburg; University of Freiburg; Freiburg Germany
3. Department of Hematology; Oncology, and Stem-Cell Transplantation; Medical Center Freiburg; University of Freiburg; Freiburg Germany
4. Institute for Medical Biometry and Statistics; Faculty of Medicine and Medical Center; University of Freiburg; Freiburg Germany