This figure illustrates how different Receiver Operating Characteristics (ROC) curves can enclose the maximum ROC Area Under the Curve (AUC), depending on the value of the acceptable false positive rate. The figure shows the graph of two curves, labelled A and B, and a straight line. The straight line, which makes a forty-five degree angle with the axes, represents the random case. Both curves A and B are above the straight line. A is above B until the curves intersect. A and B intersect at the point with x-coordinate equal to 0.3. A is then slightly below B until the two curves intersect again at the point with x-coordinate equal to 0.45. After this point, A is above B. The area under A is greater than the area under B when you consider the whole interval. However, the area under A is slightly less than the area under B when you consider values of the x-coordinate that are less than or equal to 0.45.