Youden's Index

Youden's Index is a statistic used in evaluating medical tests or diagnostic tools. It combines the test’s ability to correctly identify those with and without a condition into a single number. Specifically, it is calculated by adding the test’s sensitivity (true positive rate) and specificity (true negative rate) and then subtracting one. The value ranges from 0 to 1, where 0 indicates a test no better than random guessing, and 1 represents a perfect test. A higher Youden’s Index suggests the test is more effective at correctly distinguishing between different conditions.