Figure 2. This receiver-operator characteristic curve shows the ability of the algorithm to discriminate between markedly labile mean arterial pressure (combined anesthesiologists' ratings of 8 and 9) compared with all other anesthesia records (combined anesthesiologists' ratings of 3–7). A perfect test would result in data points overlying the leftward and upper borders of the graph, and the integral of the plot connecting the data points would be 1.0. A completely useless test would overlie the line of identity, and the integral would be 0.50. The experimental data resulted in an integral of 0.909. The line of identity is plotted for comparison with the experimental data.