In many different disciplines there is a recent increase in interest of Bayesian analysis. Bayesian methods implement Bayes' theorem, which states that prior beliefs are updated with data, and this process produces updated beliefs about model parameters. The prior is based on how much information we believe we have preceding data collection, as well as how accurate we believe that information to be. To further encourage the use of Bayesian statistics in the field of Psychotraumatology we initiated a special issue on the use of Bayesian statistics.

We first introduce briefly how and why Bayesian statistics are already being applied by means of describing the results of a systematic search in the psychotrauma field. Reasons mentioned were: Flexible hypothesis testing, Updating probabilities, No need for large data sets, Imputation of missing data, Allows to deal with technical complexities. Thereafter we describe the papers submitted as part of this special issue on Bayesian statistics. There is a recent increase in interest of Bayesian analysis.