Elff, Martin. 2019. "Strategic Voting and Ticket-Splitting in Mixed Electoral Systems: A Finite-Mixture Approach Applied to the Case of Germany". Last presented DAGStat 2019 ``Statistics under one umbrella'' 5th joint statistical meeting, 18-22 March, LMU Munich.
Why voters split their votes between elections at different (state vs federal) levels or between ballots in mixed dual vote electoral systems has been subject of a debate for several years now. A natural explanation is that ticket-splitting in mixed electoral systems is the result of various voting strategies: wasted-vote avoidance in the plurality vote on the ballot, threshold insurance in the proportional vote on the ballot, or a combination of both. Uncovering such voting strategies however has posed a considerable challenge, as they cannot be observed directly.
Despite the importance of tactical voting, no consensus has yet been reached on how to measure it. The proposed paper applies a finite-mixture discrete choice model to the case of ticket-splitting in the context of the mixed electoral system of Germany. Based on the German Election studies of 2009 through 2017 it derives the proportion of ticket-splitting that can be attributed to indifference between parties, wasted-vote avoidance, the intention to bring about a preferred coalition, or the expression of a rank-order between the first- and second-most preferred party.