Enter the likelihood of the data under the alternative hypothesis and the likelihood of the data under the null hypothesis into the calculator to determine the Bayes Factor. This calculator helps in evaluating the strength of evidence in favor of one hypothesis over another.

Bayes Factor Formula

The following formula is used to calculate the Bayes Factor (BF).

BF = frac{P(Data|H1)}{P(Data|H0)}

Variables:

  • BF is the Bayes Factor
  • P(Data|H1) is the likelihood of the data under the alternative hypothesis (H1)
  • P(Data|H0) is the likelihood of the data under the null hypothesis (H0)

To calculate the Bayes Factor, divide the likelihood of the data under the alternative hypothesis by the likelihood of the data under the null hypothesis.

What is a Bayes Factor?

The Bayes Factor is a statistical measure that quantifies the evidence in favor of one statistical model, or hypothesis, over another. It is used in Bayesian analysis to compare the predictive power of two hypotheses, typically the null hypothesis (H0) and an alternative hypothesis (H1). The Bayes Factor can be interpreted as the strength of evidence for H1 relative to H0.

How to Calculate Bayes Factor?

The following steps outline how to calculate the Bayes Factor.


  1. First, determine the likelihood of the data under the alternative hypothesis (P(Data|H1)).
  2. Next, determine the likelihood of the data under the null hypothesis (P(Data|H0)).
  3. Next, gather the formula from above = BF = P(Data|H1) / P(Data|H0).
  4. Finally, calculate the Bayes Factor (BF).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Likelihood Under Alternative Hypothesis (P(Data|H1)) = 0.4

Likelihood Under Null Hypothesis (P(Data|H0)) = 0.1

Bayes Factor (BF) = P(Data|H1) / P(Data|H0) = 0.4 / 0.1 = 4