1. What is Specificity?

Specificity is a statistical measure that evaluates a test's ability to correctly identify negative cases. It represents the proportion of actual negatives that are correctly identified as such.

2. How Does the Calculator Work?

The calculator uses the specificity formula:

Where:

• \( TN \) — True negatives (correctly identified negative cases)
• \( FP \) — False positives (incorrectly identified positive cases)

Explanation: The formula divides the number of true negative results by the sum of true negatives and false positives.

3. Importance of Specificity

Details: Specificity is crucial when the cost of a false positive is high. It's particularly important in medical testing where incorrectly diagnosing a healthy person could lead to unnecessary treatment.

4. Using the Calculator

Tips: Enter the number of true negatives and false positives from your test results. Both values must be non-negative integers, and their sum must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What's a good specificity value?
A: Generally, values above 0.9 (90%) are considered good, but the acceptable level depends on the specific application.

Q2: How does specificity relate to sensitivity?
A: Sensitivity measures true positive rate, while specificity measures true negative rate. Often there's a trade-off between them.

Q3: When is high specificity most important?
A: When the consequences of false positives are severe, such as in disease screening that might lead to invasive follow-up tests.

Q4: Can specificity be 100%?
A: In theory yes, but in practice it's rare as most tests have some false positives.

Q5: How is specificity different from precision?
A: Precision focuses on positive predictive value (true positives/all positives), while specificity focuses on true negative rate.