BallotRank: A Condorcet Completion Method for Graphs

TL;DR

BallotRank is a new Condorcet-consistent ranking method based on a modified PageRank algorithm, proven to reliably identify winners in elections and internet polls, while satisfying key social choice criteria.

Contribution

It introduces BallotRank, a novel Condorcet completion method that combines PageRank-inspired ranking with social choice properties, providing a full candidate ranking.

Findings

Always identifies the Condorcet winner at typical damping values

Satisfies many social choice criteria of established methods

Proven effective in nearly 2,000 elections and 20,000 internet polls

Abstract

We introduce BallotRank, a ranked preference aggregation method derived from a modified PageRank algorithm. It is a Condorcet-consistent method without damping, and empirical examination of nearly 2,000 ranked choice elections and over 20,000 internet polls confirms that BallotRank always identifies the Condorcet winner at conventional values of the damping parameter. We also prove that the method satisfies many of the same social choice criteria as other well-known Condorcet completion methods, but it has the advantage of being a natural social welfare function that provides a full ranking of the candidates.