Bayes Factor

The Bayes factor is a measure used in Bayesian statistics to compare the evidence provided by data for two competing hypotheses.
Given two hypotheses $H_{0}$ (the null hypothesis) and $H_{1}$ (the alternative hypothesis), the Bayes factor $B F_{10}$ is calculated as: $$BF_{1,0} = \frac{P(D|H_1)}{P(D|H_0)}$$, where $P (D | H_{1})$ is the probability of the data D given that the alternative hypothesis H1 is true, and $P (D | H_{0})$ is the probability of the data D given that the alternative hypothesis H0 is true.
It is like a Likelihood ratio test, except we integrate out the parameters, which allows us to compare models of different complexity.