Boulder County 2008 General Election Audit

The Boulder County Elections Division broke new ground in Colorado and the nation by doing one of the first audits that adhered to the "Principles and Best Practices for Post-Election Audits".

It was also perhaps the most extensive "risk-sensitive" audit to date, including 13 contests from the general election. When the margin of victory in a race is wide, that means that there would have to be problems with a large number of votes to change the outcome. So we don't have to look at many batches of votes to detect that. But if the margin is small, we have to look more closely. Traditional audits look at the same percentage of votes in each contest. Risk-sensitive audits shift the effort according to the margin of victory and are thus more efficient and effective.

Read more in the overview and in the sections below

Overview
Audit procedure
Audit reports
Audit selections using the random seed 702758241994347 from the dice rolls by the canvass board
Audit results
Results sheet with vote counts, as pdf
Results sheet with vote counts, as xls
Another audit selection example using the example random_seed of 123456789012345

Note that these data do not include provisional ballots. Also, for contests that weren't entirely within Boulder County, the data reported here for "Overall Margin" and "Proportion" of the vote are best-effort estimates. Unfortunately Colorado does not gather such data until after results are certified, and information on undervotes and overvotes, which are necessary for accurate audit margins and selections, are rarely easy to obtain from other counties.

Acknowledgments:
Credit for a multifaceted effort like this goes to many people: Boulder Clerk Hillary Hall for the leadership and resources, Crystal Christman and Scott Thomas for going beyond the call of duty, the members of the Canvass Board: Gary Boucher, Al Kolwicz, Deb Gardner and Carlos Webb for their assistance and ideas, and the hand counters and many others in the elections division. Much auditing experience came from Mark Halvorson and the members of the State Audit Working Group including Harvie Branscomb, Heleni Thayre and Pam Smith. Statistical expertise came from Ron Rivest, Raluca Popa, Javed Aslam, Arel Cordero, Kathy Dopp, Andy Bardwell, John McCarthy and the Thursday Auditing group members, including Philip Stark, Mark Lindeman, Lynn Garland, Eric Rescorla, Joseph Lorenzo Hall, Dennis Paull and Howard Stanislevic. Other contributors included Mary Eberle, Margit Johansson, Aaron D. Gerber, and Holly Lewis.
Responsibility for any problems with the audit design or implementation lies with Neal McBurnett

References:

Risk-limiting post-election audits for a more rigorous approach to error bounds, and details on the historic Marin County Measure 1A audit by Stark et al.
On Auditing Elections When Precincts Have Different Sizes by Aslam, Popa and Rivest.
A "Sum of Square Roots" (SSR) Pseudorandom Sampling Method For Election Audits by Ronald L. Rivest.
In Defense of Pseudorandom Sample Selection by Joseph A. Calandrino, J. Alex Halderman, and Edward W. Felten.

Some other audits:

ElectionAudits Data Site

This site is powered by the ElectionAudits software, which provides software and documentation in support of the Principles and Best Practices for Post-Election Audits and the other work of ElectionAudits.org, the nation's clearinghouse for election audit information.

The software is open source and can be followed at its Launchpad.net site:

https://launchpad.net/electionaudits

That is the place to get the source code, file bugs, make contributions, learn about election auditing, etc.