There are many tangled normative and technical questions involved in evaluating the quality of software used in epidemiological simulations. In this paper we answer some of these questions and offer practical guidance to practitioners, funders, scientific journals, and consumers of epidemiological research. The heart of our paper is a case study of the Imperial College London (ICL) covid-19 simulator, set in the context of recent work in epistemology of simulation and philosophy of epidemiology.
Keywords: COVID-19; Public-health policy; Simulation; Software engineering.