Referendum 2020

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.

The Populist Dynamic: Experimental Evidence on the Effects of Countering Populism (with M. Morelli, T. Tannicini, & P. Stanig), February 2024  Download

We evaluate how traditional parties may respond to populist parties on issues aligning with populist messages. During the 2020 Italian referendum on the reduction of members of Parliament, we conducted a large-scale field experiment, exposing 200 municipalities to nearly a million impressions of programmatic advertisement. Our treatments comprised two video ads against the reform: one debunking populist rhetoric and another attributing blame to populist politicians. This anti-populist campaign proved effective through demobilization, as it reduced both turnout and the votes in favor of the reform. Notably, the effects were more pronounced in municipalities with lower rates of college graduates, higher unemployment, and a history of populist votes. This exogenous influence introduced a unique populist dynamic, observable in the 2022 national election where treated municipalities showed increased support for Brothers of Italy, a rising populist party, and decreased support for both traditional parties and the populists behind the 2020 reform. A follow-up survey further showed increased political interest and diminished trust in political institutions among the residents of municipalities targeted by the campaign.

Treatments: Debunking Rhetoric & Blaming Videos

Debunking Populist Rhetoric Video

Blaming Populist Politicians Video

Experimental Design 

almost 1 million impressions in 200 municipalities in 6 regions

Informative Videos (in red) 

Emotional Video (in blue)

Randomization within Region