What does AUC-ROC measure in diagnostic test evaluation?

What does AUC-ROC measure in diagnostic test evaluation?

• A. The proportion of true positives among all positives results.
• B. Area Under the ROC Curve (AUC-ROC) measures the overall discriminative ability of a diagnostic test; 1.0 is perfect, 0.5 is no better than chance.
• C. AUC-ROC indicates the calibration of predicted probabilities.
• D. AUC-ROC is used to estimate test reliability across repeated measurements.

Answer: (B)

AUC-ROC measures how well a diagnostic test can distinguish between diseased and non-diseased individuals across all possible thresholds. The ROC curve shows sensitivity (true positive rate) versus 1 minus specificity (false positive rate) as you vary the decision threshold, and the area under that curve summarizes the test’s overall discriminative power in a single number. Think of it as the likelihood that a randomly chosen diseased person will have a higher test score than a randomly chosen non-diseased person. A perfect test reaches 1.0, meaning perfect separation at some threshold, while a test that performs no better than chance sits at 0.5. This measure focuses on ranking ability, not on calibrating predicted probabilities or on consistency across repeated measurements.

AUC-ROC measures how well a diagnostic test can distinguish between diseased and non-diseased individuals across all possible thresholds. The ROC curve shows sensitivity (true positive rate) versus 1 minus specificity (false positive rate) as you vary the decision threshold, and the area under that curve summarizes the test’s overall discriminative power in a single number.

Think of it as the likelihood that a randomly chosen diseased person will have a higher test score than a randomly chosen non-diseased person. A perfect test reaches 1.0, meaning perfect separation at some threshold, while a test that performs no better than chance sits at 0.5.

This measure focuses on ranking ability, not on calibrating predicted probabilities or on consistency across repeated measurements.