Receiver operating characteristic (ROC)

A plot of true positive rate against false positive rate while a decision threshold varies over a fixed evaluation population. A random ranking has an expected diagonal curve; a perfect ranking reaches the upper-left corner.

The integral of the receiver operating characteristic's true positive rate with respect to its false positive rate. Equivalently, the probability that a randomly selected positive is ranked above a randomly selected negative, with half weight for ties. It measures discrimination rather than probability calibration or utility at a particular threshold.