Martin Schumacher1, Kristin Ohneberg2, Jan Beyersmann3. 1. Institute for Medical Biometry and Statistics, Faculty of Medicine and Medical Center-University of Freiburg, Stefan-Meier-Straße 26, 79104 Freiburg, Germany. Electronic address: sec@imbi.uni-freiburg.de. 2. Institute for Medical Biometry and Statistics, Faculty of Medicine and Medical Center-University of Freiburg, Stefan-Meier-Straße 26, 79104 Freiburg, Germany. 3. Institute of Statistics, Ulm University, Helmholtzstr. 20, 89081 Ulm, Germany.