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JAMA Guide to Statistics and Methods
September 8, 2015

Evaluating Discrimination of Risk Prediction Models: The C Statistic

Author Affiliations
  • 1Biostatistics and Bioinformatics, Duke Clinical Research Institute, Duke University, Durham, North Carolina
  • 2Department of Mathematics and Statistics, Boston University, Boston, Massachusetts
JAMA. 2015;314(10):1063-1064. doi:10.1001/jama.2015.11082

Risk prediction models help clinicians develop personalized treatments for patients. The models generally use variables measured at one time point to estimate the probability of an outcome occurring within a given time in the future. It is essential to assess the performance of a risk prediction model in the setting in which it will be used. This is done by evaluating the model’s discrimination and calibration. Discrimination refers to the ability of the model to separate individuals who develop events from those who do not. In time-to-event settings, discrimination is the ability of the model to predict who will develop an event earlier and who will develop an event later or not at all. Calibration measures how accurately the model’s predictions match overall observed event rates.