A year of progress in post-election audits

Philip B. Stark, Professor of Statistics, UC Berkeley

Abstract: Any system for counting votes is subject to error. Is the aggregate error material--did it change the apparent winner? Risk-limiting audits guarantee a pre-specified minimum chance that the audit will lead to a full manual count of the ballots whenever that manual count would show a different electoral outcome. The theory, law and practice of post-election audits have progressed considerably over the last year. Fourteen months ago, there was no viable method for risk-limiting audits; now there are several. A pilot risk-limiting audit was conducted in Marin County, California in February 2008, and more are currently underway in Humboldt, Marin, Santa Cruz and Yolo counties. I will present up-to-the-minute results from these audits, and an overview of the methods they use.