In my previous posts, I’ve been discussing ballot-level comparison audits, a form of risk-limiting audit. Ballots are imprinted with serial numbers (after they leave the voter’s hands); during the audit, a person must find a particular numbered ballot in a batch of a thousand (more or less). With CCOS (central-count optical scan) this works fine: […]

In my previous posts, I’ve been discussing ballot-level comparison audits, a form of risk-limiting audit. Ballots are imprinted with serial numbers (after they leave the voter’s hands); during the audit, a person must find a particular numbered ballot in a batch of a thousand (more or less). If the ballot papers are numbered consecutively, that’s […]

In my last article, I posed this puzzle for the reader. We want to do ballot-level comparison audits, a form of RLA (risk-limiting audit) on a precinct-count optical-scan (PCOS) voting system. This requires a serial number printed on every ballot, linked with an entry in the cast-vote-record (CVR) file. The standard method is to pick […]

Special bonus: This article contains two puzzles for the reader, marked in green. Try to solve them yourself before reading the solutions in a future post! In my last post I described a particularly efficient kind of risk-limiting audit (RLA) of election results: ballot-level comparison audits, which rely on a unique serial number on every […]

All voting machines these days are computers, and any voting machine that is a computer can be hacked to cheat. The widely accepted solution is to use voting machines to count paper ballots, and do Risk-Limiting Audits: random-sample inspections of those paper ballots to ensure (with a guaranteed level of assurance) that the election outcome […]