This talk was presented at the online seminar on Mathematical Modelling of Epidemics organized by Prof. Ralf Meyer at the University of Göttingen. We first discussed Bayesian inference and then closely followed the article on Inferring change points in the spread of COVID-19 reveals the effectiveness of interventions by Jonas Dehning, Johannes Zierenberg, F. Paul Spitzner, Michael Wibral, Joao Pinheiro Neto, Michael Wilczek, and Viola Priesemann (Science 369 (2020), no. 6500). This talk was not directly related to my research area; however, I found the topic interesting and decided to feature it. The material should be accessible for bachelor students.