Modeling Persuasion within Small Groups, with an Application to a Deliberative Field Experiment on U.S. Fiscal Policy

We propose a new method to measure persuasion within small groups, and apply this method to a large scale randomized deliberative experiment. We define persuasion as the systematic component of an individual's preference change that is due to discursive interpersonal interaction, and we measure this systematic component using a spatial model that captures dependence in policy preferences among participants randomly assigned to discussion groups. Our method separately measures persuasion in an ideological space from persuasion in a non-ideological, topic-specific space. The functional form of our model accommodates tests of substantive hypotheses found in the small group literature on small group polarization. To illustrate the methods we present an application in which we examine how changes in participants' policy views on U.S. fiscal policy in a large-scale randomized experiment resulted from the composition of the small discussion groups to which they were randomly assigned.