Measuring the impact of consultative citizen participation: reviewing the congruency approaches for assessing the uptake of citizen ideas

As academic and political interest in citizen participation and democratic innovations is growing, the question of their impact on public policy remains essential to assess their genuine contribution to the normative project of democratization. Impact assessments of consultative participatory mechanisms are commonly conducted with a congruency approach—a desk-based research method which assesses impact based on the textual correspondence between a citizen-created idea and public policy documents. This method, however, lacks reliability and uniformity, and this paper therefore seeks to standardize its application and ways to improve the accuracy of its results by proposing two methodological add-ons. First, a sequential impact matrix that considers the preferences of decision-makers before a consultative participatory mechanism to see the extent to which decision-makers take up citizen ideas that align with or diverge from their own agenda. Second, a mixed method that combines a congruency approach with interviews of actors involved in the follow-up of the participatory process to balance their experiences with the congruency approach’s main findings. The variants of the congruency approach are then applied to a deliberative minipublic—the citizen panel ‘Brussels—Make Your Mobility’. This analysis shows how these methodological strategies alter the impact assessment’s results, and its findings suggest that the use of a sequential impact matrix with a mixed method not only produces an accurate and reliable measurement but also generates valuable insights into the diffuse ways in which minipublics can exert substantial influences on the institutional structures and the political decision-making. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11077-022-09450-w.