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Post-Election Audits

top 4 reasons to conduct post election audits

Pennsylvania counties currently conduct two types of post-election analyses: a statistical sample required by law and a statewide risk-limiting audit (RLA) which will be implemented in each county by the November 2022 election.

Post-Election Analysis

As currently required as part of the computation and canvass of returns, counties must complete the statistical sample required by law (25 P.S. § 3031.17).

A county board of elections is required to conduct a statistical sample of a random sample of at least 2% of the ballots cast or 2,000 ballots, whichever number is fewer.

In 2019 and 2020, the Department of State piloted additional risk-limiting audits at the county level and across the Commonwealth. One of the goals of these pilots was to test models and best practices for enhanced post-election audits that are scientifically designed to strengthen election integrity, confirm the accuracy of election outcomes, and ensure voter confidence.

Risk-Limiting Audit

Pennsylvania's statewide risk-limiting audit of the November 2020 presidential election was completed in February 2021.

Sixty-three participating counties reviewed a statistical sample of over 45,000 randomly selected ballots from the November 3, 2020, General Election. The results of the sample mirrored the reported presidential election results across the participating counties within a fraction of a percentage point, providing confirmation of the accuracy of the vote count. 

To conduct this specific pilot:

    • Counties created ballot manifests, which are spreadsheets identifying the organization of and numbers of cast ballots in each county. All ballot types were included –  in-person, mail-in, absentee and provisional. 
    • After the counties uploaded their manifests to the audit software, a random seed number was generated, and the audit software selected the random list of ballots to be retrieved by each county.
    • The 63 participating counties retrieved the ballots, indicated the vote cast for the presidential contest on each ballot, and the system tallied and analyzed the results.
    • The results of the sample mirrored the reported presidential election results across the participating counties within a fraction of a percentage point, providing strong evidence of the accuracy of the vote count.

"The RLA was a great tool that reinforced that the results of the presidential race were done accurately and securely. The process allowed for members of all interested parties to be involved in the process by reviewing a random sample of ballots in a nonpartisan fashion." Michael Anderson, Director of Lebanon County Bureau of Elections.

About Risk-Limiting Audits

Risk-limiting audits are scientifically designed procedures that use statistical methods to confirm election outcomes and to detect possible interference. RLAs examine a random sample of paper ballots, comparing the votes on paper to the totals reported by the vote-counting machines to ensure that the winner actually won. These types of audits can confirm that voting systems tabulated the paper ballots accurately enough that a full hand count would produce the same outcome. 


County election officials, Department of State staff, and election experts from the Brennan Center for Justice at NYU School of Law, National Vote at Home Institute, Verified Voting, and VotingWorks participated in developing and implementing the RLA pilot.

"We're proud to partner with state and local election officials to help them implement the gold standard of post-election audits to protect voter confidence in the integrity of our elections." Liz Howard, senior counsel, Brennan Center for Justice at NYU School of Law.

The Department of State certified nine new voting systems for use by the counties. Each system provides a voter verifiable paper record of each vote cast, meets the latest standards of security and accessibility and can be thoroughly audited. 

Every voting system and paper ballot in Pennsylvania must include plain text that voters can read to verify their choices before casting their ballot, and every system has successfully completed penetration testing, access-control testing and testing to ensure that every access point, software and firmware are protected from tampering. Many other important recommendations by national security and cybersecurity experts are in place in Pennsylvania, including mandatory pre-election testing of all voting equipment.


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