Post Election Audits

Tabulation starts with ballots people have cast and ends with vote totals that determine the outcome of each contest in an election. Tabulation is more than just adding up numbers that represent votes. Tabulation also includes the separate, preliminary step of determining voter intent — did this voter vote for this choice in this contest? — from the marks on the ballot.

Good tabulation audits provide solid evidence to support public trust in the ultimate outcomes of elections.  In particular, the public deserves evidence that the vote-counting computers are accurately recording and counting the votes.

Why Audit Tabulations?
Nearly all US votes today are counted by computerized voting systems. Such voting systems have produced outcome-changing errors through problems with hardware, software, and procedures. Errors can also occur in hand counting of ballots or in the canvassing of results. Even serious errors can go undetected if results are not audited effectively. Well-designed and properly performed post-election tabulation audits provide solid public evidence for the initial tabulation outcome when it is correct — and an opportunity to recover gracefully when it is not. Good tabulation audits create resilience against damage from human error, system flaws or malicious hacking, and should be applied routinely to any voting system in each and every election. The benefits of such audits include: deterring hacking, malware, and fraud; finding error, whether accidental or intentional; recovering from error and producing correct outcomes via a full hand count; providing for continuous improvement in the conduct of elections; promoting public confidence in elections.
What is a Risk-Limiting Audit (RLA)?
Risk-limiting audits are designed to ensure strong audit evidence that a reported outcome is correct – if the outcome is indeed correct. For more detail see the Risk-Limiting Audit page.
Is a Fixed-Percentage Audit the Same As a Risk-Limiting Audit?
Fixed-percentage audits — the practice of recounting by hand a certain percentage of ballots, or all the ballots in a certain percentage of precincts — can sometimes detect errors in computer tabulations.  However, these audits either count too few ballots to provide solid evidence for correctness, or count more — sometimes far more — ballots than necessary. The fixed-percentage election audits implemented in many states in the twentieth century are particularly inefficient because they are based on sampling whole precincts or other large batches of ballots.  For close contests, or situations where errors are clustered in only a few precincts, such a fixed-percentage audit might run a large risk of letting an incorrect outcome go undetected. The disadvantage of sampling based on precincts or other large batches can be explained in terms of soup and jelly beans.
What Are the Post-Election Audit Laws In My State?
As of 2018, many states are considering changes to their audit laws and procedures. Consult the Verified Voting Audit Law database, or contact your state election agency.
Is a Tabulation Audit the Same As a Recount?
Tabulation audits differ from recounts. Tabulation audits routinely check voting system performance. Recounts repeat ballot counting in special circumstances, such as when preliminary results show a close margin of victory. Post-election audits that detect errors can lead to a full recount if the margin of victory is very small or if the audit detects errors and therefore cannot achieve the risk-limit.
How Can I Find Out More?
Read about principles and best practices, legislation, implementationaudit algorithms and oversight of post-election tabulation audits.
Denver Elections Division’s Risk-Limiting Audit (2018)

Colorado’s Risk-Limiting Audit (2017)