A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods

Counting votes is complex and error-prone. Several statistical methods have been developed to assess election accuracy by manually inspecting randomly selected physical ballots. Two ‘principled’ methods are risk-limiting audits (RLAs) and Bayesian audits (BAs). RLAs use frequentist statistical infer...

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Main Authors: Huang, Zhuoqun, Rivest, Ronald L, Stark, Philip B., Teague, Vanessa J., Vukcevic, Damjan
Other Authors: Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory
Format: Book
Language:English
Published: Springer International Publishing 2021
Online Access:https://hdl.handle.net/1721.1/129969
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author Huang, Zhuoqun
Rivest, Ronald L
Stark, Philip B.
Teague, Vanessa J.
Vukcevic, Damjan
author2 Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory
author_facet Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory
Huang, Zhuoqun
Rivest, Ronald L
Stark, Philip B.
Teague, Vanessa J.
Vukcevic, Damjan
author_sort Huang, Zhuoqun
collection MIT
description Counting votes is complex and error-prone. Several statistical methods have been developed to assess election accuracy by manually inspecting randomly selected physical ballots. Two ‘principled’ methods are risk-limiting audits (RLAs) and Bayesian audits (BAs). RLAs use frequentist statistical inference while BAs are based on Bayesian inference. Until recently, the two have been thought of as fundamentally different. We present results that unify and shed light upon ‘ballot-polling’ RLAs and BAs (which only require the ability to sample uniformly at random from all cast ballot cards) for two-candidate plurality contests, that are building blocks for auditing more complex social choice functions, including some preferential voting systems. We highlight the connections between the methods and explore their performance. First, building on a previous demonstration of the mathematical equivalence of classical and Bayesian approaches, we show that BAs, suitably calibrated, are risk-limiting. Second, we compare the efficiency of the methods across a wide range of contest sizes and margins, focusing on the distribution of sample sizes required to attain a given risk limit. Third, we outline several ways to improve performance and show how the mathematical equivalence explains the improvements.
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spelling mit-1721.1/1299692022-09-27T14:49:02Z A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods Huang, Zhuoqun Rivest, Ronald L Stark, Philip B. Teague, Vanessa J. Vukcevic, Damjan Massachusetts Institute of Technology. Computer Science and Artificial Intelligence Laboratory Counting votes is complex and error-prone. Several statistical methods have been developed to assess election accuracy by manually inspecting randomly selected physical ballots. Two ‘principled’ methods are risk-limiting audits (RLAs) and Bayesian audits (BAs). RLAs use frequentist statistical inference while BAs are based on Bayesian inference. Until recently, the two have been thought of as fundamentally different. We present results that unify and shed light upon ‘ballot-polling’ RLAs and BAs (which only require the ability to sample uniformly at random from all cast ballot cards) for two-candidate plurality contests, that are building blocks for auditing more complex social choice functions, including some preferential voting systems. We highlight the connections between the methods and explore their performance. First, building on a previous demonstration of the mathematical equivalence of classical and Bayesian approaches, we show that BAs, suitably calibrated, are risk-limiting. Second, we compare the efficiency of the methods across a wide range of contest sizes and margins, focusing on the distribution of sample sizes required to attain a given risk limit. Third, we outline several ways to improve performance and show how the mathematical equivalence explains the improvements. 2021-02-22T22:59:54Z 2021-02-22T22:59:54Z 2020-09 2021-02-04T16:58:16Z Book http://purl.org/eprint/type/ConferencePaper 9783030603465 9783030603472 0302-9743 1611-3349 https://hdl.handle.net/1721.1/129969 Huang, Zhuoqun et al. "A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods." E-Vote-ID: International Joint Conference on Electronic Voting, Lecture Notes in Computer Science, 12455, Springer International Publishing, 2020, 112-128. © 2020 Springer Nature en http://dx.doi.org/10.1007/978-3-030-60347-2_8 Lecture Notes in Computer Science Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Springer International Publishing arXiv
spellingShingle Huang, Zhuoqun
Rivest, Ronald L
Stark, Philip B.
Teague, Vanessa J.
Vukcevic, Damjan
A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods
title A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods
title_full A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods
title_fullStr A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods
title_full_unstemmed A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods
title_short A Unified Evaluation of Two-Candidate Ballot-Polling Election Auditing Methods
title_sort unified evaluation of two candidate ballot polling election auditing methods
url https://hdl.handle.net/1721.1/129969
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