The Benefits of Applying Bayes’ Theorem in Medicine

The present article provides a very basic introduction to Bayes’ theorem and its potential implications for medical research. This introduction was written to be accessible to medical researchers without much mathematical background in general or without much background in Bayesian mathematics specifically. I prove Bayesian equations from very basic probability theorems and also show how these basic theorems can aid medical researchers to make important discoveries without having to do much empirical work. In many cases, the necessary empirical work, including relevant epidemiological work, is already in the medical literature and important discoveries can be made merely by looking up that work and applying one of the Bayesian equations to be presented. I also demonstrate that the traditional null hypothesis significance testing procedure that currently dominates medical research is blatantly invalid; a Bayesian point of view suggests that researchers should not use this procedure. Finally, I discuss some special issues, including philosophical issues that pertain to using a Bayesian perspective in medicine.