Department of Medical Statistics, University Medical Center Göttingen, D-37099 Göttingen, Germany. Klaus.Jung@ams.med.uni-goettingen.de|Department of Medical Statistics, University Medical Center Göttingen, D-37099 Göttingen, Germany. Klaus.Jung@ams.med.uni-goettingen.de|Department of Medical Statistics, University Medical Center Göttingen, D-37099 Göttingen, Germany. Klaus.Jung@ams.med.uni-goettingen.de