Examining Voting Spillover Effects of Text Message Reminders

We present results from a pre-registered, well-powered $(N \gt 3,000,000)$ text message get-out-the-vote (GOTV) experiment, conducted during the 2019 European Parliament election in Sweden. Our findings suggest that a simple text message increases the likelihood of voting by 0.3 percentage points. Half of this effect spills over to untreated household members while workplace spillovers are near zero. Subsequent analysis reveals that the direct treatment effect is noticeably stronger among individuals with below-average voting propensities. Interestingly, within this same group, the household spillovers are significantly negative. We speculate and provide some indirect evidence, that these negative spillover effects may stem from the text message reminder influencing the behaviour of voters already motivated to vote. Above all, we propose that an increase in early voting, as opposed to voting on Election Day, among treated individuals may weaken the mechanisms thought to explain spillover effects since voters are less likely to bring their family members with them when voting early.