# Chapter 4 Bayesian and Frequentist Statistics

The idea of frequentist statistics is by beginning with the assumption that the mean difference between the two groups is zero and the sample data (null hypothesis) offer the evidence to support or reject the null hypothesis. Bayesian thinking allows us to assert a prior belief that the two groups may differ—the evidence provided by the sample data updates and modifies our prior belief. If we have additional probability information, we can calculate the likelihood of a specific scenario in light of new evidence.