part 5: receiver operating characteristic curve and area under the curve

multiple diagnostic tools are used by emergency physicians, every day. in addition, new tools are evaluated to obtain more accurate methods and reduce time or cost of conventional ones. in the previous parts of this educational series, we described diagnostic performance characteristics of diagnostic tests including sensitivity, specificity, positive and negative predictive values, and likelihood ratios. the receiver operating characteristics (roc) curve is a graphical presentation of screening characteristics. roc curve is used to determine the best cutoff point and compare two or more tests or observers by measuring the area under the curve (auc). in this part of our educational series, we explain roc curve and two methods to determine the best cutoff value.