Doing More With Less: Mismatch-Based Risk-Limiting Audits

Fuente: arXiv
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Main Authors: Ek, Alexander, Blom, Michelle, Stark, Philip B., Stuckey, Peter J., Teague, Vanessa J., Vukcevic, Damjan
Format: Preprint
Published: 2025
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author Ek, Alexander
Blom, Michelle
Stark, Philip B.
Stuckey, Peter J.
Teague, Vanessa J.
Vukcevic, Damjan
author_facet Ek, Alexander
Blom, Michelle
Stark, Philip B.
Stuckey, Peter J.
Teague, Vanessa J.
Vukcevic, Damjan
contents One approach to risk-limiting audits (RLAs) compares randomly selected cast vote records (CVRs) to votes read by human auditors from the corresponding ballot cards. Historically, such methods reduce audit sample sizes by considering how each sampled CVR differs from the corresponding true vote, not merely whether they differ. Here we investigate the latter approach, auditing by testing whether the total number of mismatches in the full set of CVRs exceeds the minimum number of CVR errors required for the reported outcome to be wrong (the "CVR margin"). This strategy makes it possible to audit more social choice functions and simplifies RLAs conceptually, which makes it easier to explain than some other RLA approaches. The cost is larger sample sizes. "Mismatch-based RLAs" only require a lower bound on the CVR margin, which for some social choice functions is easier to calculate than the effect of particular errors. When the population rate of mismatches is low and the lower bound on the CVR margin is close to the true CVR margin, the increase in sample size is small. However, the increase may be very large when errors include errors that, if corrected, would widen the CVR margin rather than narrow it; errors affect the margin between candidates other than the reported winner with the fewest votes and the reported loser with the most votes; or errors that affect different margins.
format Preprint
id arxiv_https___arxiv_org_abs_2503_16104
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Doing More With Less: Mismatch-Based Risk-Limiting Audits
Ek, Alexander
Blom, Michelle
Stark, Philip B.
Stuckey, Peter J.
Teague, Vanessa J.
Vukcevic, Damjan
Computers and Society
Cryptography and Security
Applications
One approach to risk-limiting audits (RLAs) compares randomly selected cast vote records (CVRs) to votes read by human auditors from the corresponding ballot cards. Historically, such methods reduce audit sample sizes by considering how each sampled CVR differs from the corresponding true vote, not merely whether they differ. Here we investigate the latter approach, auditing by testing whether the total number of mismatches in the full set of CVRs exceeds the minimum number of CVR errors required for the reported outcome to be wrong (the "CVR margin"). This strategy makes it possible to audit more social choice functions and simplifies RLAs conceptually, which makes it easier to explain than some other RLA approaches. The cost is larger sample sizes. "Mismatch-based RLAs" only require a lower bound on the CVR margin, which for some social choice functions is easier to calculate than the effect of particular errors. When the population rate of mismatches is low and the lower bound on the CVR margin is close to the true CVR margin, the increase in sample size is small. However, the increase may be very large when errors include errors that, if corrected, would widen the CVR margin rather than narrow it; errors affect the margin between candidates other than the reported winner with the fewest votes and the reported loser with the most votes; or errors that affect different margins.
title Doing More With Less: Mismatch-Based Risk-Limiting Audits
topic Computers and Society
Cryptography and Security
Applications
url https://arxiv.org/abs/2503.16104