Abstract
This paper describes a participatory approach to co-designing social simulation models with policymakers using a case study of modeling European Commission policy. Managing the collaboration of a wide range of individuals or organizations is challenging but increasingly important as policy making becomes more complex. A framework for a co-design process based on a participatory approach is proposed. The framework suggests that the collaborative design should go through the following phases: Identifying user questions, data provision, model discussion for validation, visualization of results and discussing scope and limitations with stakeholders. Key findings are that the co-design process requires communication skills, patience, willingness to compromise, and motivation to make the formal world of modelers and the narrative world of policymaking meet. Furthermore, especially in participatory modeling scenarios, stakeholders have to be included not only in the provision of data, but also in order to confirm the existence, quality and availability of data.