Candidate Incentive Distributions: How voting methods shape electoral incentives
Marcus Ogren
TL;DR
The paper addresses how voting method choice shapes political incentives to reach across voter groups, introducing the Candidate Incentive Distribution ($CID$) as a quantitative measure of centripetal incentives. Using computer simulations across multiple voting rules, it finds that Condorcet methods, STAR, and Approval Top 2 provide the most balanced incentives, while Instant Runoff Voting and Plurality-based rules are more inclined to favor a candidate's base. Strategic voting patterns tend to dampen differences in incentives, though $CID$ remains notably more balanced under Condorcet-type and cardinal methods. The work offers practical guidance for reform efforts aiming at depolarization and cross-cutting appeal, and provides open-source code for replication and extension.
Abstract
We evaluate the tendency for different voting methods to promote political compromise and reduce tensions in a society by using computer simulations to determine which voters candidates are incentivized to appeal to. We find that Instant Runoff Voting incentivizes candidates to appeal to a wider range of voters than Plurality Voting, but that it leaves candidates far more strongly incentivized to appeal to their base than to voters in opposing factions. In contrast, we find that Condorcet methods and STAR (Score Then Automatic Runoff) Voting provide the most balanced incentives; these differences between voting methods become more pronounced with more candidates are in the race and less pronounced in the presence of strategic voting. We find that the incentives provided by Single Transferable Vote to appeal to opposing voters are negligible, but that a tweak to the tabulation algorithm makes them substantial.