A receiver operating characteristic (ROC) is a graph that illustrates the performance of a binary classifier as its discrimination threshold (cutoff) is changed.

The curve is created by plotting the true positive rate (TPR) against the false positive rate (FPR) at various cutoff settings. The true-positive rate is known as sensitivity, the false-positive rate is known as the fall-out and is calculated as (1 - specificity).

The ROC curve is thus a plot of the true positives (TPR) versus the false positives (FPR). The ROC curve can be generated by plotting the cumulative distribution function (area under the probability distribution from - ∞ to + ∞ ) of the correct detection probability in the y-axis versus the cumulative distribution function of the false-alarm probability in x-axis.