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Improved Methods For Post-Election Audit Sampling

New Improved Methods For Post-Election Audit Sampling

By The National Election Data Archive
Park City, UT July 17, 2009
Origainl URL

Summary: A new monumental research paper that was begun in January 2009 is now finished. “Checking election outcome accuracy – Post-election audit sampling” significantly advances and improves upon existing risk-limiting post-election audit sampling methodology.”

According to Kathy Dopp, the report’s author, “New more precise methods show that somewhat larger, more conservative sample sizes are needed in order to achieve a desired high minimum probability to detect and correct any initial incorrect election outcomes.

This new article advances and improves existing post-election audit sampling methodology by using more precise methods. Post-election audit sampling methods have been the subject of extensive recent research. This article

* provides an overview of post-election audit sampling research and compares various approaches to calculating post-election audit sample sizes, focusing on risk-limiting audits,

* discusses fundamental concepts common to all risk-limiting post-election audits, presenting new margin error bounds, sampling weights and sampling probabilities that improve upon existing approaches and work for any size audit unit and for single or multi-winner election contests,

* provides two new simple formulas for estimating post-election audit sample sizes in cases when detailed data, expertise, or tools are not available,

* summarizes four improved methods for calculating risk-limiting election audit sample sizes, showing how to apply precise margin error bounds to improve the accuracy and efficacy of existing methods, and

* discusses common sampling mistakes that reduce post-election audit effectiveness.

Adequate post-election audit sampling is crucial because analyzing discrepancies found in too-small samples can determine little except that the sample size is inadequate.

This article is one of three new articles in a series “Checking Election Outcome Accuracy”. The other two articles discuss post-election auditing procedures and an algorithm for deciding whether to increase the sample or to certify the election outcome in response to discrepancies found during a post-election audit.

The new methods involve using new precise upper margin error bounds. Read the entire article Checking Election Outcome Accuracy -- Post-Election Auditing Sampling on-line at: or at

Other recent items that may be of interest to voters:

1. Thanks, responses, and *corrections* to the USE-nix “2009 Electronic Voting Technology Workshop / Workshop on Trustworthy Elections” reviewers who rejected the same article.

USE-nix reviewers are invited to post anonymous responses to Kathy Dopp's response to their reviews at my blog: (or exactly at this URL)

2. US Count Votes endorses and encourages support for HR2894, “The Voter Confidence & Increased Accessibility Act of 2009” (search for the latest version)

3. Analysis of the “Voter Confidence & Increased Accessibility Act of 2009” (VC Bill)

4. The newest big threat to US election fairness and integrity after e-ballots: “Realities Mar Instant Runoff Voting -- 18 Flaws and 4 Benefits”, February 2009 version

5. Report on the 2009 Burlington, VT IRV Mayoral election

Contact: Kathy Dopp or

The National Election Data Archive is a 501(c)(3) nonprofit organized for educational and scientific purposes of promoting fair and accurate elections by researching, developing and promoting methods and procedures to detect voter disenfranchisement and vote count inaccuracy. Such methods include independent manual vote count audits, exit poll discrepancy analysis, and the public release and scientific analysis of election data along with public release of election records necessary to verify the integrity of elections.


Kathy Dopp

The material expressed herein is the informed product of the author's fact-finding and investigative efforts. Dopp is a Mathematician, Expert in election audit mathematics and procedures; in exit poll discrepancy analysis; and can be reached at

Realities Mar Instant Runoff Voting - 18 Flaws and 4 Benefits

Voters Have Reason to Worry

© Scoop Media

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