Bernoulli Ballot Polling: A Manifest Improvement for Risk-Limiting Audits

Understand

We present a method and software for ballot-polling risk-limiting audits (RLAs) based on Bernoulli sampling: ballots are included in the sample with probability $p$, independently.

• Bernoulli sampling has several advantages: (1) it does not require a ballot manifest; (2) it can be conducted independently at different locations, rather than requiring a central authority to select the sample from the whole population of cast ballots or requiring stratified sampling; (3) it can start in polling places on election night, before margins are known.
• If the reported margins for the 2016 U.S.
• Presidential election are correct, a Bernoulli ballot-polling audit with a risk limit of 5% and a sampling rate of $p_0 = 1\%$ would have had at least a 99% probability of confirming the outcome in 42 states.