Mathematics
The Bayes Factor as a Tool for Hypothesis Testing
Quick fact
A Bayes factor of 10 means the data are 10 times more likely under one hypothesis than the other, but it does not mean the first hypothesis is true with 10/11 probability—that depends on your prior.
Why this is interesting
You've probably heard of p-values, but what if there were a more direct way to compare two hypotheses—one that tells you exactly how much the data favor one over the other?