Internal and External Effects on the Accuracy of NES Turnout: Reply

Abstract

In an earlier issue of this journal I brought attention to the fact that estimates of voter turnout in U.S. presidential elections from the National Election Study (NES) series have been increasingly biased. Although researchers had already noted that the NES overestimated turnout, I was concerned with the growing severity of the problem. While admitting that other factors were at work, my explanation centered on the representativeness of surveys, in particular that selection bias in the sample is correlated with the likelihood of voting (Burden 2000). Martinez (2003) and McDonald (2003) offer three possible additions to my argument. First, panel effects are responsible for particularly egregious discrepancies in a few presidential elections, particularly in the 1996 survey. Second, official turnout statistics that rely on the Voting Age Population (VAP) are themselves biased and lack perfect comparability with the NES. Third, the degree of misreporting might also depend on actual voter turnout.