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