Post Test Probability Calculator

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

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?

  1. First, determine the pre test odds.

    Calculate the pretest odds.

  2. Next, determine the likelihood ratio.

    Calculate the likelihood ratio.

  3. Finally, calculate.

    Calculate the post-test probability using the formulas above.


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.

post test probability calculator
post test probability formula