Beyond personal vote incentives: Dividing the vote in preferential electoral systems

Comparative studies of preferential electoral systems have paid much attention to the incentives for personalized instead of party-centered campaigns, but they have largely ignored how some of these systems allow “allocation errors” and so create incentives for parties to “manage” the vote and intraparty campaigns. We discuss how the single non-transferable vote (SNTV) and single transferable vote (STV) systems create these incentives, and we illustrate the degree to which they affect actual electoral results across seven preferential electoral systems. The analysis reveals statistically significant differences in the vote inequality among incumbent cohorts (members of the same party and district), indicating the strong influence of vote division incentives over candidate-centered electoral environments. The results also have important implications for comparative research on legislative turnover and the incumbency advantage.

► Electoral systems that allow allocation error punish intraparty vote inequalities.
► We examine vote divisions among same-party-district incumbents in seven countries.
► Vote inequalities are smaller where allocation errors are more likely.
► Parties' incentives to divide the vote systematically affect the “personal vote”.