training deep leaning models precision and recall are often visualized using pr curvewhich plots precision on the axis and recall on the axis (see figure - different values of precision and recall can be obtained by varying the decision threshold on the score or the probability the model produces--for instance implying class aand implying class bwith higher value on one side indicating particular class this curve can be used to trade off precision for recall by varying the threshold figure - pr curve pr where denotes precision and denotes + recallcan be used to summarize the pr curve the receiver operating characteristic (roccurve is useful in cases of class imbalance and unequal misclassification costs in this settingexamples are said to belong to two classespositive and negative the -scoredefined as