Preference change in stakeholder group-decision processes in the public sector: Extent, causes and implications

Public decisions are typically related to large investments leaving long legacies. We should therefore strive for wide societal agreement regarding such decisions, which meet the diversity of preferences between stakeholders and over time. But if, how and why do stakeholder preferences change over time? In decision analysis, these questions received little attention. We explored them using three real-world public decision processes, based on Multi-Criteria Decision Analysis (MCDA). We used repeatedly elicited ranking of objectives over time. These were obtained during three to five moderated workshops we organised several months apart (total N = 200 questionnaires, and 100 stakeholders). We analysed individual and aggregated (group) preferences, their changes and potential drivers including demographic and experience variables. We also analysed the effect of preference evolution on the performance of decision-alternatives with MCDA over time. We found that stakeholder preferences often changed over time, both on an individual and group level. These changes did not systematically diminish over time, but some convergence of preferences was observed for stakeholders who repeatedly participated in workshops. High-ranking objectives were relatively stable and similar between stakeholders. While preference changes could not be explained by demographics and personal experiences, repeated interaction with the decision problem might play a role. Neither the observed disagreement between stakeholders, nor the preference changes over time affected the best and worst performing alternatives in our decision problems. Thus, despite changing stakeholder preferences over time, public decision-makers can contrive robust solutions to complex public decision problems in the present.