Data Source and Methodology
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The Formula Explained
\[
\text{PPV} = \frac{\text{True Positives}}{\text{True Positives} + \text{False Positives}} \times 100
\]
Glossary of Variables
- True Positives: The number of correctly identified positive cases.
- False Positives: The number of incorrectly identified positive cases.
- PPV: Positive Predictive Value, the probability that subjects with a positive test truly have the disease.
How It Works: A Step-by-Step Example
Imagine a test with 80 true positives and 20 false positives. Using the formula, the PPV is:
\[
\text{PPV} = \frac{80}{80 + 20} \times 100 = 80\%
\]
Frequently Asked Questions (FAQ)
What is Positive Predictive Value (PPV)?
PPV is the probability that subjects with a positive screening test truly have the disease.
Why is PPV important?
It helps determine the effectiveness of a diagnostic test, crucial for clinicians in making informed decisions.
How does PPV differ from sensitivity?
Sensitivity is the ability of a test to correctly identify those with the disease. PPV focuses on the probability of true disease presence among positive results.