Politics in the facebook era. Evidence from the 2016 US presidential elections

Abstract

Social media allow political campaigns to reach specific groups of voters with unprecedented precision, yet the effect on voting behaviour of this political micro-targeting is still uncertain. To identify this effect we match survey data with a novel indicator of Facebook political ads intensity, based on audience-specific ad prices and collected during the 2016 US presidential campaign. We find that being exposed to Facebook micro-targeted ads reduced the likelihood of persuading Democrat respondents to cast the ballot in favour of the Democrat candidate and, on the other hand, it increased the likelihood of persuading Republicans and residents of traditionally red or swing states to switch their vote in favour of Mr Trump. A counterfactual analysis exercise exploring the effect on voter mobilisation and persuasion of varying the intensity of political campaigning on Facebook confirms that Trump was the primary beneficiary of micro-targeted ad campaigns on Facebook.