1. What is Specificity?

Specificity is a statistical measure that determines the ability of a test to correctly identify negative cases. It's the proportion of true negatives that are correctly identified by the test.

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 calculates the ratio of correctly identified negative cases to all actual negative cases.

3. Importance of Specificity

Details: Specificity is crucial in diagnostic tests where correctly identifying negative cases is important, such as screening tests where false positives could lead to unnecessary treatments.

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 the difference between specificity and sensitivity?
A: Sensitivity measures how well a test identifies positive cases, while specificity measures how well it identifies negative cases.

Q2: What is a good specificity value?
A: Generally, specificity above 90% is considered good, though this depends on the clinical context.

Q3: How does specificity relate to false positive rate?
A: Specificity = 1 - false positive rate. They are complementary measures.

Q4: Can specificity be 100%?
A: Yes, if there are no false positives (all negative cases are correctly identified).

Q5: Why is specificity important in screening tests?
A: High specificity reduces unnecessary follow-up tests and anxiety from false positive results.