doi: 10.1016/j.jclinepi.2017.11.013. Epub 2017 Nov 24. Ewout W Steyerberg 1 , Hajime Uno 2 , John P A Ioannidis 3 , Ben van Calster 4 , Collaborators Collaborators, Affiliations Affiliations 1 Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands; Department of Public Health, Erasmus MC, Rotterdam, The Netherlands. Electronic address: e.w.steyerberg@lumc.nl. 2 Division of Population Sciences, Dana-Farber Cancer Institute, 02215 MA, Boston, USA.