Calculate a Bayes factor to compare the evidence for two hypotheses.
The Bayes factor quantifies how much the data shift belief between two hypotheses, independently of the prior. Unlike a p-value it can provide evidence for the null rather than merely failing to reject it. A Bayes factor below one is positive evidence for the null, which no p-value can ever express.
Bayes Factor
BF₁₀ = P(data | H₁) ÷ P(data | H₀); posterior odds = prior odds × Bayes factor
BF₁₀ = P(data | H₁) ÷ P(data | H₀); posterior odds = prior odds × Bayes factor The Bayes factor quantifies how much the data shift belief between two hypotheses, independently of the prior. Unlike a p-value it can provide evidence for the null rather than merely failing to reject it.
A Bayes factor below one is positive evidence for the null, which no p-value can ever express.
This calculator takes 3 inputs: Likelihood under hypothesis 1, Likelihood under the baseline hypothesis, Prior odds for hypothesis 1. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.