Group proximity and mutual understanding: Measuring onsite impact of a citizens' summit

To better understand the impact of deliberations during participatory policymaking events, we introduce and explore the concept of group proximity. An example of such events is citizens' summits, during which many parallel groups deliberate on solutions for a policy issue. At the summit that was studied, each group followed a value deliberation process with the aim to increase mutual understanding among participants. They were asked to rank the solutions in their order of preference before and after the deliberation. From these rankings, group proximity can be calculated with a rank correlation, enabling a precise comparison of participants' preferences in each deliberative group. High group proximity indicates very similar rankings in a deliberative group, while low group proximity demonstrates the opposite. Comparing group proximity of the before and after rankings shows if a group ranked convergent, unchanged or divergent. This measure allows for a quantitative analysis of early-stage public policymaking processes.