Quantifying parliamentary representation of constituents’ preferences with quasi-experimental data

We analyze the effect of constituents’ preferences on legislators’ decisions within a quasi-experimental setting: In the Swiss referendum process, constituents and legislators vote on policy proposals and thus reveal their preferences. We match roll call votes of all legislators on 118 legislative proposals with revealed constituents’ preferences on exactly the same issues from 1996 to 2009. This setting allows us to quantify the quality of parliamentary representation. Results show that the probability of a legislator accepting a law proposal increases slightly when his/her constituency accepts the proposal and we explore mediating factors that affect congruence between legislators and constituents.