Prediction error in the chain ladder method

We define a chain ladder model which allows for the study of three different error types: (a) diversifiable process error, (b) non-diversifiable process error, and (c) parameter estimation error. The model is based on the classical stochastic chain ladder model introduced by Mack [Mack, T., 1993. Distribution-free calculation of the standard error of chain ladder reserve estimates. Astin Bull. 23(2), 213–225]. In order to clearly distinguish the different sources of prediction uncertainty, we have to slightly modify that classical chain ladder model.