How to use
- Enter TP, FP, TN, and FN from one operating threshold.
- Optionally rename the positive and negative labels.
- Compare Youden’s J beside balanced accuracy and the raw rates before choosing a cutoff.
Wave 8 diagnostic metrics
Threshold quality from sensitivity and specificity
Youden’s J is useful when you want one compact threshold score without losing sight of the underlying rates.
Inputs
Run a calculation to review Youden’s J, sensitivity, specificity, and false-positive rate.
Why Youden’s J is useful
Youden’s J moves from 0 toward 1 as sensitivity and specificity improve together. It is helpful when you want one threshold summary without ignoring either side of the confusion matrix.
If you still need to compare score rankings rather than one fixed threshold, move to ROC AUC. If you want odds-style evidence, move to likelihood ratio.
Frequently asked questions
What is Youden’s J?
Youden’s J equals sensitivity plus specificity minus one. It summarizes how far a threshold moves away from random guessing while balancing true-positive and true-negative performance.
When should I use Youden’s J?
Use it when you want one threshold-focused score that rewards both sensitivity and specificity at the same time. It is useful for comparing nearby cutoffs.
Is Youden’s J the same as balanced accuracy?
They are closely related. Balanced accuracy equals the average of sensitivity and specificity, while Youden’s J equals sensitivity plus specificity minus one.
Does the share URL include my counts or labels?
No. The share URL stores only lightweight settings such as decimal places. Counts and custom labels stay in your browser.
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