When it comes to loss reserving, actuaries often find themselves juggling complex data and uncertain future outcomes. One powerful tool in their arsenal is Bayesian credibility theory, which combines historical data with expert judgment to provide a more robust estimate of outstanding claims. For those preparing for the CAS exams, mastering Bayesian credibility theory can be a game-changer, especially in the context of accident year reserving. In this article, we’ll explore four practical techniques for applying Bayesian credibility theory to accident year reserving, along with practical examples and actionable advice to help you ace your exams.