1. What Are Sensitivity And Specificity?

Sensitivity (true positive rate) measures the proportion of actual positives correctly identified. Specificity (true negative rate) measures the proportion of actual negatives correctly identified. These are fundamental metrics for evaluating diagnostic tests.

2. How The Calculator Works

The calculator uses these standard formulas:

Where:

• \( TP \) — True Positives (correctly identified cases)
• \( FN \) — False Negatives (missed cases)
• \( TN \) — True Negatives (correctly rejected cases)
• \( FP \) — False Positives (incorrectly identified cases)

Explanation: Sensitivity focuses on how well the test detects actual cases, while specificity focuses on how well it excludes non-cases.

3. Importance Of These Metrics

Details: These metrics are crucial for understanding a test's performance. High sensitivity is important when missing a case is dangerous. High specificity is important when false alarms are costly.

4. Using The Calculator

Tips: Enter all four values (TP, FN, TN, FP) as whole numbers. The calculator will compute both sensitivity and specificity as percentages.

5. Frequently Asked Questions (FAQ)

Q1: What's a good sensitivity/specificity value?
A: Generally >90% is excellent, 80-90% is good, but ideal values depend on the clinical context.

Q2: Can a test have 100% sensitivity and specificity?
A: In theory yes, but in practice perfect tests are extremely rare due to biological variability.

Q3: What's more important - sensitivity or specificity?
A: It depends. Screening tests often prioritize sensitivity, while confirmatory tests prioritize specificity.

Q4: How are these different from PPV and NPV?
A: PPV (positive predictive value) and NPV (negative predictive value) depend on disease prevalence, while sensitivity/specificity don't.

Q5: What if my denominator is zero?
A: The calculator requires valid denominators (TP+FN > 0 and TN+FP > 0) to prevent division by zero.