title: Prediction models need appropriate internal, internal-external, and external validation.
authors.affiliation: Department of Public Health, Erasmus MC, Rotterdam, The Netherlands. Electronic address: e.steyerberg@erasmusmc.nl.
authors.forename: Ewout W
authors.initials: EW
authors.lastname: Steyerberg
authors.affiliation: Department of Biostatistics, School of Medicine, Vanderbilt University, Nashville, TN, USA.
authors.forename: Frank E
authors.initials: FE
authors.lastname: Harrell
mesh_terms: D005544:Forecasting; D008962:Models, Theoretical; D054928:Validation Studies as Topic