Have we all underestimated the severity of socioeconomic differences in electoral participation?

Opinion polls routinely overestimate voter turnout, since participants misreport their own voting record, and because politically engaged voters are also more likely to respond to surveys. Using unique linked survey and register-based data from Finland that allows them to measure the effects of these biases, Hannu Lahtinen, Pekka Martikainen, Mikko Mattila, Hanna Wass, and Lauri Rapeli demonstrate that these two factors also lead to an underestimation of socioeconomic differences in turnout. The results imply that social inequality in political participation is a greater social challenge than previously thought.