Fig. 2

Receiver operating characteristic (ROC) space with “target region” based on minimally acceptable criteria for accuracy. ROC space has two dimensions: sensitivity (y-axis) and 1-specificity (x-axis). When the sum of sensitivity and specificity is ≥ 1.0, the test’s accuracy will be a point somewhere in the upper left triangle. The “target region” of a diagnostic accuracy study will always touch the upper left corner of ROC space, which is the point for perfect tests, where both sensitivity and specificity are 1.0. From there, the rectangle extends down, to MAC for sensitivity, and extend to the right, towards MAC for specificity. The gray square represents the target region of a diagnostic accuracy study with a MAC (sensitivity) of 0.70, and a MAC (specificity) of 0.60. MAC, minimally acceptable criteria