Department of Medical Informatics, Biometry and Epidemiology, University of Munich, Marchioninistr. 15, Munich, D-81377, Germany. hornung@ibe.med.uni-muenchen.de.|Department of Medical Informatics, Biometry and Epidemiology, University of Munich, Marchioninistr. 15, Munich, D-81377, Germany. boulesteix@ibe.med.uni-muenchen.de.|Applied Mathematics Department, Agrocampus Ouest, 65 rue de St. Brieuc, Rennes, 35042, France. David.Causeur@agrocampus-ouest.fr.