Election turnout is central to the health of a democracy. However, measuring election turnout in opinion surveys is problematic due to misreporting. Research shows that survey respondents over-report their turnout so as to give a socially desirable answer. Studies show that over-reporting is more prevalent among partisan respondents and those who are more politically interested. Other studies have concentrated on non-response bias as a cause of turnout misreporting. However, most existing research is country-specific and does not take into account system characteristics or survey administration variables. Using 20-years of data from Comparative Study of Electoral Systems (CSES) covering 150 elections across 40 different states, this paper examines the importance of the political system and survey administration in the overreporting of turnout. The results suggest that overreporting occurs less often in more democratic states, countries that have compulsory voting, and in countries where the survey is conducted by personal interview. Conversely, overreporting is more prevalent when elections are held in the summer, in countries where there are more parties, and in election studies that use telephone surveys. Our results have implications for how we understand and correct for turnout overreporting in national election studies.
