We document the effectiveness of robo calls for increasing voter participation despite most published research finding little or no effect of automated calls. We establish this finding in a large field experiment in a targeted, partisan get-out-the-vote campaign. Our experimental design includes a follow-up call, which allows us to control for selection effects. We identify subsets of subjects, for whom the treatment effects are substantially larger than those that are found in previous studies. Our findings show that robo calls can cause a one percentage point increase in voter turnout. Additionally, our experimental design allows for testing how the number of calls in a treatment, that is dosage, affects voter turnout. Here, results show that that a few extra calls increase the treatment effect, and that many additional calls decrease that effect.
political advertising voter turnout selection effects field experiment