We ran a large-scale field experiment and a survey experiment during the electoral campaign for the September 2020 referendum in Italy. A constitutional law was passed in 2019, which reduced the number of MPs from 630 to 400 in the Lower House and from 315 to200 in the Senate. A petition was later filed by 71 Senators to hold a constitutional referendum to repeal the law. We obtained electoral material designed and provided by a committee promoting the “No” vote, that is, against the cut in the number of MPs, for its national campaign. We used a novel communication tool, programmatic advertisement, to send almost a million impressions to Italian citizens in 200 municipalities of six Italian regions (Campania, Emilia-Romagna, Lazio, Lombardia, Toscana, and Veneto). These impressions consisted of two non-skippable pre-roll videos displayed in a large host of websites, including newspapers, blogs, games, etc.
Our randomization was done at the municipal level. One video was more factual and provided information on the negative consequences that reducing the number of MPs would have for the democratic representativeness of the Parliament. The other video was more emotional and brought a more direct attack to the politicians who promoted the reduction of the number of MPs We also ran a survey experiment with around 2,000 individuals from the same municipalities of the field experiment and administered the same treatments to the sample.
Treatments: Informative & Emotional Videos
almost 1 million impressions in 200 municipalities in 6 regions
Informative Videos (in red)
Emotional Video (in blue)
Randomization within Region