Models to understand the impact of management practices on retail performance are often simplistic and assume low levels of noise and linearity. Of course, in real-life, retail operations are dynamic, non-linear and complex. To overcome these limitations, we investigate discrete-event and agent-based modelling and simulation approaches. The joint application of both approaches allows us to develop simulation models that are heterogeneous and more life-like, though poses a new research question: When ng such simulation models one still has to abstract from the real world, however, ideally in such a way that the `essence' of the system is still captured. The question is how much detail is needed to capture this essence, as simulation models eveloped at different levels of abstraction. In the literature the appropriate abstraction for a particular case study is often more of an art than a science. In this paper, we aim to study this question more systematically by using a retail bra...