1. What is False Positive Rate?

The False Positive Rate (FPR) is the proportion of negative cases that are incorrectly identified as positive by a test. In pregnancy testing, it measures how often the test incorrectly indicates pregnancy when none exists.

2. How Does the Calculator Work?

The calculator uses the False Positive Rate formula:

Where:

• \( FP \) — False Positives (incorrect positive results)
• \( TN \) — True Negatives (correct negative results)

Explanation: The FPR represents the probability that the test will falsely indicate pregnancy when the woman is not actually pregnant.

3. Importance of FPR Calculation

Details: Understanding FPR is crucial for evaluating the reliability of pregnancy tests. A lower FPR indicates a more reliable test with fewer false alarms.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What is a good FPR for pregnancy tests?
A: Most high-quality pregnancy tests aim for an FPR below 1% (0.01). The lower the FPR, the better.

Q2: How does FPR differ from false discovery rate?
A: FPR measures false positives among all negative cases, while false discovery rate measures false positives among all positive test results.

Q3: Can FPR be zero?
A: In theory yes, but in practice all tests have some false positives. A reported FPR of zero usually means the sample size was too small.

Q4: What factors affect FPR in pregnancy tests?
A: Test quality, user error, evaporation lines, certain medications, and medical conditions can all increase FPR.

Q5: How is FPR related to specificity?
A: Specificity = 1 - FPR. High specificity means low false positive rate.