A First Approach to Risk-Limiting Audits for Single Transferable Vote Elections

TL;DR

This paper introduces the first risk-limiting audit method tailored for 2-seat single transferable vote elections, addressing the complexity of vote interactions unique to STV systems.

Contribution

It develops an initial approach to RLAs specifically for 2-seat STV elections, filling a gap in election auditing methods for complex voting systems.

Findings

Proposes a novel RLA method for 2-seat STV elections

Addresses the complexity of vote transfers in STV audits

Lays groundwork for extending RLAs to more complex STV elections

Abstract

Risk-limiting audits (RLAs) are an increasingly important method for checking that the reported outcome of an election is, in fact, correct. Indeed, their use is increasingly being legislated. While effective methods for RLAs have been developed for many forms of election -- for example: first-past-the-post, instant-runoff voting, and D'Hondt elections -- auditing methods for single transferable vote (STV) elections have yet to be developed. STV elections are notoriously hard to reason about since there is a complex interaction of votes that change their value throughout the process. In this paper we present the first approach to risk-limiting audits for STV elections, restricted to the case of 2-seat STV elections.