[In]Credible Models – Verification, Validation & Accreditation of Agent-Based Models to Support Policy-Making

This paper explores the issue of model credibility of agent-based models and how it should be evaluated prior to application in policy-making. Specifically, the paper analyses related literature from different fields: (1) to establish a definition of model credibility – a measure of confidence in the model’s inferential capability – and (2) to assess how model credibility can be strengthened through Verification, Validation, and Accreditation (VV&A) prior to application and through post-application evaluation. Several studies have highlighted seriousshortcomings in how V&V of agent-based models is performed and documented, and few public administrations have an established model accreditation process. To address the first issue, we examine the literature on model V&V and, based on this review, introduce and outline the use of a V&V plan. To address the second issue, we draw inspiration from a practical use case of model accreditation applied by a government institution to propose a framework for the accreditation of agent-based models for policy-making. The paper concludes with a discussion of the risks associated with inappropriate assessments of model credibility.