ROC curves

Receiver operating characteristic (ROC) curves：Signal detection theory (Radar)

Key

1. Sensitivity is on y axis, 1 – specificity on x-axis (100% - specificity if using percent)

2. Area under the ROC curve is generally between 0.5 (useless) to 1.0 (perfect)

3. Area is proportional to ability of a test to discriminate diseased from non-diseased. It is an important tool for comparing tests.

4. It is useful for identifying the best cutoff to define an abnormal test

5. Slope of a curve = y/x = Se / (100-Sp)

6. The slope at any point on the curve is also the positive likelihood ratio!

7. Closest to upper left corner. Youden’s J: point that maximizes sensitivity + specificity - 1