How much work is involved in a risk-limiting audit (RLA)?
The effort required for a risk-limiting audit depends on a variety of factors, including how ballots are sorted and stored, and the margins of the contests. Recent experience shows RLAs are cost-effective. RLAs can reduce overall audit burden by allocating more resources to closer contests where more checking is needed to validate outcomes. See the “Risk-Limiting Audits: Scope and Methods” section of Risk-Limiting Post-Election Audits: Why and How.
Which voting systems features affect risk-limiting audits?
Any voting system with voter-marked paper ballots can be audited with risk-limiting techniques. A system that imprints identification numbers on ballots at the time of scanning can make the ballot-pulling process more efficient. A system that can match the computer’s interpretation of each individual paper ballot to the ballot itself can dramatically reduce the number of ballots audited in close contests.
How can voter anonymity be preserved?
When auditing less common ballot types or very small precincts, care must be taken to preserve voter anonymity and the secrecy of the individual voter’s ballot. Also, it may be possible to confirm the election outcome without sampling some types of ballots, if these types do not contain enough ballots to alter the outcome. However, for fairness and to provide valuable information about the quality of the election process, all ballot types should be routinely audited.
What software is available to support risk-limiting audits?
To calculate random samples and determine how many ballots to audit, there is an Audit Tools web page developed and maintained by Professor Philip Stark. For an open source system for input of ballot information and coordination between jurisdictions, see the GitHub repository developed for the Colorado Department of State and maintained by Free & Fair.
For more on audit implementation, see Are you ready to audit? and Why would an election administrator want to do risk-limiting audits?