Moreno Mancosu (Collegio Carlo Alberto)

“The strength of weak political ties: Discussion networks and the diffusion of Movimento 5 Stelle in 2013 Italian Elections”

Abstract

The article aims to analyze the development of vote intentions for a new populist party, Movimento 5 Stelle (the 5 Star Movement), during the campaign for the 2013 Italian general election. The party, headed by a former comedian, Beppe Grillo, gained 25% of valid votes in the election, thus becoming the largest party in the Italian political landscape. Using rolling cross-sectional, pre-election data from the Italian National Election Study (ITANES), it is shown that intentions to vote for the 5 Star Movement rise over the campaign, in a fashion that is consistent with a diffusion process, especially when people are exposed to political discussants coming from non-cohesive social groups (for instance, friends). This is consistent with the idea of the “strength of weak ties” exposed by Mark Granovetter. The trend of the process is tested by means of multilevel regression models and underlying mechanisms are tackled by means of an Agent-Based Model (ABM) calibrated with actual data of 2013 election campaign. Results coming from this latter model substantially confirm hypotheses and show interesting patterns concerning negative word-of-mouth in diffusion processes.