The Effect of the Leaders on Coalition’s Governments: Evidence from a Conjoint Experiment

Most studies about the formation of political coalitions focus on political parties’ motivations (office-seeking and policy-seeking motivations) and institutions which favor alliances. However, in real political life, government alliances are triggered regardless the number of parties involved, or their varying ideologies. The personal characteristics of politicians have been ignored as drivers of coalition formation. This paper asks whether and how similarity of leaders’ characteristics has any effect on coalition formation (homophily principle). Through a conjoint experiment included in a survey of 900 Spanish Mayors, this paper pretends to demonstrate a causal relationship between similarities in sociodemographic characteristics (gender, age and level of education) and coalitions and the mechanisms why individual characteristics might matter. The experiment evaluates how politicians make decisions in certain situations, where they have to choose a partner to govern between two randomly varied candidates’ profiles. The election between candidates for a possible local coalition government during the negotiation process is a familiar situation for party leaders. The experiment is provided to Mayors because they play the role of leading the government formation process and have the power to propose a coalition. The experimental data shows that the characteristics of political leaders matters in the decision-making process. Second, it demonstrates that personal characteristics have a causal role defining some combinations of coalitions between similar profiles of leaders. This paper contributes to the literature about coalitions’ formation by demonstrating a specific mechanism through which the personal characteristics of leaders can affect their decisions on government formation process. It also contributes to the existing and growing debate about the importance of individual factors of the leaders in their decision-making processes.