https://doi.org/10.1177/0192512118824459 International Political Science Review 1–14 © The Author(s) 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0192512118824459 journals.sagepub.com/home/ips Does talking matter? A quasi-experiment assessing the impact of deliberation and information on opinion change Eoin O’Malley Dublin City University, Ireland David M Farrell University College, Dublin, Ireland Jane Suiter Dublin City University, Ireland Abstract Deliberative democracy is for many the most significant development in democratic theory in the last 50 years and it has been used in some places to solve real-world policy problems. However, measuring the impact of deliberative methods is not clearly achievable because several independent variables are manipulated simultaneously. One of the main goals of deliberation is opinion change and thus it is important to understand why opinions change. This paper utilises comparison groups in order to isolate the impact of deliberation from information in the deliberative process. We outline the results of a quasi-experiment in which deliberation took place in a citizens’ assembly (CA) in Ireland. As part of this we measured the impact using pre- and post-test controls, including a group given the information the CA participants received, but without the deliberation. The results of the analysis provide evidence of a separate deliberation effect. Keywords Deliberations, participatory democracy, information processing, citizens’ assemblies, Ireland Introduction: Deliberation and opinion change When citizens make decisions, it is often thought to be on the basis of information. For this reason governments provide information, and in certain types of elections – for instance, referendums Corresponding author: Eoin O’Malley, School of Law and Government, Dublin City University, Dublin 9, Ireland. Email: eoin.omalley@dcu.ie 824459IPS 0 0 10.1177/0192512118824459International Political Science ReviewO’Malley et al. research-article 2019 Article