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Audit PowerPoint Presentation

Audit

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Audit

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Presentation Transcript

  1. Audit • Purpose of Audit • Quality assurance procedure • Check accuracy of machine tally of ballots • Ballots for a contest are sampled, manually verified, and results checked against vote tabulation • Boulder County’s Audit • Risk-minimizing approach – minimize risk of confirming an incorrect election outcome • Meets “higher level of statistical confidence” part of CRS 1-7-514 • Selecting contests – probability proportional to the inverse of the contests’ margin. Close contests more likely to be selected. • Selecting Ballots – statistical algorithm which uses the contest’s margin, weighting by the number of times the contest appears in a batch, and random selection. • Uncontested contests ignored

  2. Audit Contest & Batch Selection Batch Reporting Zero Cum 1 Tally MBB 1 MBB 2 …. MBB 3 Cum 2 … Cum n

  3. Contest Selection Example C 2 C 3 Contest 1 0 0.9570 1.0 0.8700

  4. Contest Selection Caveats • Select contests one at a time until the audit budget has been reached. • Contests having unopposed candidates (or no candidates) will not be audited. • Contests involved in a recount will be ignored. Their results will be audited after the recount.

  5. Batch Selection • Algorithm Used – Negative Exponential (NEGEXP) • Proposed in 2008 by Aslam, Popa, and Rivest • Ballot batches selected for audit with probability based on the number of times the contest appears in the batch. • Number of batches to audit determined by the desired confidence that any outcome-impacting error, if present, would be found. • Better operational efficiency in large elections. • Requires a large number of random numbers  use random number generator • Additional Constraints • Additional batches added to ensure all scanners are audited at least once. • Canvass board may nominate batches to be audited.

  6. 2014 Primary Election Canvass Reconciliation & Audit Schedule