Replication Data for: Differential Registration Bias in Voter File Data: A Sensitivity Analysis Approach

The widespread availability of voter files has improved the study of political participation in American politics, but the lack of good data on non-registrants creates difficult inferential issues. Most notably, observational studies that examine turnout rates among registrants often implicitly condition on registration, a post-treatment variable that can induce bias if the treatment of interest also affects the likelihood of registration. We introduce a sensitivity analysis to assess the potential bias induced by this problem, which we call differential registration bias. Our approach is most helpful when only a cross-section of registrants is available, but is also useful when when the voting-eligible population is estimated from secondary sources. We illustrate our approach with two studies of voting eligibility effects on subsequent turnout among young voters. In both cases, eligibility appears to decrease turnout, but these effects are found to be highly sensitive to differential registration bias.