Institute for Medical Informatics, Biometry and Epidemiology, University of Duisburg-Essen, Hufelandstr. 55, D-45122 Essen, Germany. markus.neuhaeuser@medizin.uni-essen.de <markus.neuhaeuser@medizin.uni-essen.de>|Institute for Medical Informatics, Biometry and Epidemiology, University of Duisburg-Essen, Hufelandstr. 55, D-45122 Essen, Germany. markus.neuhaeuser@medizin.uni-essen.de <markus.neuhaeuser@medizin.uni-essen.de>