Spatial Models of Party Competition Applied
An application of spatial models of party competition presupposes the construction of policy spaces which encompass the important policy issues of an election. These are the basis of policy voting by the electorate and of strategic position taking by parties. In addition to policy voting, individual vote functions have to include party valences and long-term commitments of voters to parties. After having estimated such vote functions for several Bundestag elections, our aim is to study equilibrium dynamics of party competition under the impact of mixed electoral systems. For pure electoral systems the folk wisdom is that first past the post induces centripetal party movements, and proportional representation induces centrifugal positioning, especially of low-valence parties. Our research question is how voters respond to the opportunity to cast two ballots and how parties come to terms with the possibly differing equilibrium dynamics of mixed-member electoral systems.
The German mixed member electoral system challenges parties to develop campaign strategies at both the national and the constituency level. Nash equilibria based on separate vote functions for candidate and party list votes suggest that for high valence parties the plurality tier generates stronger centripetal incentives than the proportional tier, whereas low valence parties, normally having no chance to win the district mandate, face even stronger centrifugal tendencies under plurality rule (Kurella/Pappi/Bräuninger 2015).
Generally, district candidates do not enjoy much leeway to deviate from the policy position of their party but try to capitalize on their own valence profile. The most important valence characteristic here is being known to the local electorate. Relying on data on voter perceptions, however, may bias estimates of valence characteristics. Respondents knowing name and party of a candidate are for most the partisans of that party resulting in self-selection (Pappi/Kurella, under review). Districts where nationally prominent candidates and locally known incumbents compete provide better opportunities to study contamination effects between candidate and party list votes as shown in the publication of Bräuninger/Pappi 2015.