Area under the Curve

Figure 1. Area under the curve for Assay result
Area under the curve for Assay result

The area under the curve represents the probability that the assay result for a randomly chosen positive case will exceed the result for a randomly chosen negative case. The asymptotic significance is less than 0.05, which means that using the assay is better than guessing.

While the area under the curve is a useful one-statistic summary of the accuracy of the assay, you need to be able to choose a specific criterion by which blood samples are classified and estimate the sensitivity and specificity of the assay under that criterion. See the coordinates of the curve to compare different cutoffs.

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