Enter the pre-test probability and the likelihood ratio into the calculator to determine the post-test probability.

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## Post-Test Probability Formula

The following equation is used to calculate the post-test probability.

Pre Test Odds = P/(1 – P) = 0.012

Post Test Odds = Pre Test Odds * LR

Post Test Probability = Post Test Odds/(1 + Post Test Odds)

- Where P is the pre-test probability
- LR is the likelihood ratio

## Post-Test Probability Definition

Post-test probability as defined as the chance of an event occurring given a pre-test probability and pre-test odds.

## Post-Test Probability Example

How to calculate Post-Test Probability?

**First, determine the pre test odds.**Calculate the pretest odds.

**Next, determine the likelihood ratio.**Calculate the likelihood ratio.

**Finally, calculate.**Calculate the post-test probability using the formulas above.

## FAQ

**What is post test probability?**

A post test probability is the likelihood for an event to occur given a starting pre test probability, and pre-test odds.