Dalela, Asmita

Kulyk, Oksana

Schürmann, Carsten

English

Risk-limiting audits (RLAs) are expected to strengthen the public confidence in the correctness of an election outcome. We hypothesize that this is not always the case, in part because for large margins between the winner and the runner-up, the number of ballots to be drawn can be so small that voters lose confidence. We conduct a user study with 105 participants resident in the US. Our findings confirm the hypothesis, showing that our study participants felt less confident when they were told the number of ballots audited for RLAs

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Voter Perceptions of Trust in Risk-LimitingAuditsAsmita Dalela1, Oksana Kulyk1, and Carsten Schürmann1IT University of Copenhagen, Denmark{asmd,okku,carsten}@itu.dkMotivation: A Risk-limiting audit (RLA) [2] is a post-election auditingtechnique that is gaining increasing popularity, because it can automaticallycorrect a wrong election outcome, while being very efficient especially if themargins are wide. The purpose of RLAs has been to strengthen public confidencein the election, first, because they can be integrated into existing election processes,for example, in Denmark, where the result of the first (rough) count can be verifiedduring the second (fine) count [3]. Second, some of the ceremonies surroundingRLAs can be turned into public events, such as the dice-rolling ceremony usedto create entropy to select a random sample.The question, however, remains open, whether RLAs really strengthen publicconfidence. While the theory behind the audits is sound, the resulting samplesize is often very small (e.g. 523 ballots audited in an RLA given a total of393,826 cast votes in the 2020 election in Denver, Colorado). Thus it remains anopen question whether the voters would find an audit with such a sample sizeconvincing or not.Method: To answer the research question if RLAs really strengthen publicconfidence in the outcome of an election, we conducted a user study with 105randomly chosen US residents across all demographics using the Prolific platform.We study several hypothesis, most importantly:1:H1,1 When asked about their opinions about which number of ballots should beselected for auditing, the participants provide a number higher than the oneprescribed by the RLA methodology.H1,2 Participants’ confidence in the audit results changes when they are informedabout the number of ballots selected for auditingResults: When asked which number of ballots the participants would preferto be audited, this number tended to be magnitudes higher than the actualnumber required by the RLA for most of the participants (see Figure 1). The signtest has confirmed that the difference between preferred and actual number ofballots is significantly different from zero (p < .001, 95% CI for median differencebetween preferred and actual ballots (as percentage of total ballots) is [3.23%,16.1%]), thus, H1,1 is confirmed.While the majority of the participants (70%, 74 out of 105) had a positiveattitude towards conducting RLAs, choosing either “maybe yes” or “definitely1 For a more detailed description of the methodology and the rest of tested hypothesesand conducted analyses, see the extended version of the paper [1]2 Asmita Dalela, Oksana Kulyk, and Carsten Schürmannyes” as the answer to the question whether their confidence in the election resultwould increase after an RLA, only 44% provided a positive answer to the samequestion asked after presenting the number of audited ballots to the participants.Figure 1 shows the distribution of changes of participants’ answers. The Wilcoxonsigned-rank test shows a significant difference between the “before” and “after”answers (p < .001, Z = −4.47, effect size r = .33, moderate), thus, H1,2 isconfirmed.Fig. 1: Left: Preferred vs. actual number audited ballots (as percentage of totalballots) depending on the margin. The scale is logarithmic. Right: Percentage ofparticipants for each case of confidence change.Conclusion: We recognize the value of RLAs in confirming the integrity ofthe election result. However, our results show that as a measure to create trust,they are not sufficient by themselves, and additional measures such as votereducation need to be considered. While this study is the first one to investigatethis issue, follow-up work is needed to better understand the factors influencingvoter’s trust and the effectiveness of various ways one can educate voters aboutRLAs or raise trust via other measures.References1. Asmita Dalela, Oksana Kulyk, and Carsten Schürmann. Voter perceptions of trustin risk-limiting audits, 2021.2. Mark Lindeman and Philip B. Stark. A gentle introduction to risk-limiting audits.IEEE Security & Privacy, 10(5):42–49, 2012.3. Carsten Schürmann. A risk-limiting audit in Denmark: A pilot. In First InternationalJoint Conference on Electronic Voting and Identity (E-Vote-ID’16), pages 192 – 202.Springer Verlag LNCS 10141, October 2016.

Voter Perceptions of Trust in Risk-Limiting Audit

https://pure.itu.dk/portal/files/86390718/Trust_in_RLAs_E_Vote_ID_12.pdf

Voter Perceptions of Trust in Risk-Limiting Audit

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