How Accurate are Surveyed Preferences for Public Policies? Evidence from a Unique Institutional Setup

Opinion polls are widely used to capture public sentiments on a variety of issues. If citizens are unwilling to reveal certain policy preferences to others, opinion polls may fail to characterize population preferences accurately. The innovation of this paper is to use unique data to measure biases in opinion polls for a broad range of policies. I combine data on 184 referenda held in Switzerland between 1987 and 2007, with post-ballot surveys that ask for each proposal how the citizens voted. The difference between stated preferences in the survey and revealed preferences at the ballot box provides a direct measure of bias in opinion polls. I find that these biases vary by policy areas, with the largest ones occurring in policies on immigration, international integration, and votes involving liberal/conservative attitudes. Also, citizens show a tendency to respond in accordance to the majority