Data Source and Methodology
Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti dalla MSD Manual.
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.
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
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Formula (extracted LaTeX)
\[\text{PPV} = \frac{\text{True Positives}}{\text{True Positives} + \text{False Positives}} \times 100\]
\text{PPV} = \frac{\text{True Positives}}{\text{True Positives} + \text{False Positives}} \times 100
Formula (extracted LaTeX)
\[\text{PPV} = \frac{80}{80 + 20} \times 100 = 80\%\]
\text{PPV} = \frac{80}{80 + 20} \times 100 = 80\%
Formula (extracted text)
\[ \text{PPV} = \frac{\text{True Positives}}{\text{True Positives} + \text{False Positives}} \times 100 \]
Formula (extracted text)
\[ \text{PPV} = \frac{80}{80 + 20} \times 100 = 80\% \]
Variables and units
- No variables provided in audit spec.
Sources (authoritative):
- MSD Manual — msdmanuals.com · Accessed 2026-01-19
https://www.msdmanuals.com/professional/multimedia/clinical-calculator/positive-predictive-value-of-a-test
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.