Research question/goal:

In multi-party systems, parties often announce their coalition preferences during the electoral campaign. Our project focused on two aspects. The first was to understand how pre-electoral coalition signals influence voting behaviour. The second was to investigate under which conditions parties are willing to send coalition signals during election campaigns.

To explore how coalition signals shape voting behaviour, we conducted four different survey experiments during the 2018 Swedish general election, the 2020 Irish general election, the 2020 New Zealand general election, and the 2021 German federal election. To test when parties signal their preferred coalitions, we set up a comprehensive cross-country database of electoral coalitions in 398 legislative elections in 22 advanced industrialized democratic countries from 1946 to 2014. Furthermore, we collected pre-electoral coalition signals from newspaper articles in 17 elections in five countries. Using this extensive data set, we worked together with computer scientists from the University of Mannheim to train a classifier that automatically detects coalition signals from newspaper articles.

Our results provide central insights into the influence of coalition signals on voting decisions. First, coalition signals affect voting decisions by changing voters' expectations about which coalitions are likely to form after the election. Second, voters are risk-averse with respect to coalition-directed voting. Third, breaking coalition promises reduces the propensity of voters to vote for the inconsistent parties. Fourth, motivation, information, and capabilities are preconditions for strategic voting. With respect to parties' pre-electoral coalition strategies, parties prefer to form pre-electoral coalitions with partners who are on the same side of the ideological spectrum.