Specificity Calculator
Enter true negatives and false positives to evaluate diagnostic specificity and understand test performance for negative cases.
Specificity: 80.00%
Formula: TN / (TN + FP)
Negative cases: 100
How to Use This Calculator
- Enter true negatives (correctly identified negatives).
- Enter false positives (incorrectly identified negatives).
- Review the reported specificity as a percentage.
- Use results to evaluate specificity, true negative rate, or precision for negative outcomes.
Formula
Specificity = TN / (TN + FP)
Represents the true negative rate.
Denominator equals total actual negatives.
Full Description
Specificity measures the probability that a diagnostic test correctly identifies negative cases. High specificity reduces false alarms, crucial for avoiding unnecessary follow-up procedures and ensuring confidence in negative results.
Frequently Asked Questions
What if there are no negative cases?
Specificity is undefined when TN + FP = 0. The calculator alerts you to this situation.
How does specificity relate to sensitivity?
Specificity gauges correct negatives; sensitivity targets correct positives. Both evaluate complementary aspects of accuracy.
Can specificity exceed 100%?
No. With valid counts, specificity ranges between 0% and 100%.
How can specificity be improved?
Increase true negatives relative to false positives, often by adjusting thresholds or refining test criteria.