Moving the campaign from the front door to the front pocket: field experimental evidence on the effect of phrasing and timing of text messages on voter turnout

Despite the widespread scholarly attention given to get-out-the-vote tactics the recent one and a half decade, few have studied the effect of short text messages (SMS) on voter turnout, and no previous such study has been conducted outside the US. We analyze four SMS experiments with more than 300,000 voters conducted in relation to two elections in Denmark and find intention-to-treat (ITT) effects between 0.33 and 1.82 percentage points with a pooled effect of 0.74 percentage points. Furthermore, we vary the timing and the content of the messages to test existing theories of text messages as mobilization tools. In one experiment, we find messages delivered before Election Day to have a higher effect than those delivered on Election Day, while we find no additional effect of delivering multiple messages. We also vary message content and in general find no significant differences from sending different messages.