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2018 Primary Election: Post-Election Ballot Tabulation Audit


Following the 2018 Primary Election, this office will conduct a post-election ballot tabulation audit.  The tabulation audit will be conducted in addition to the comprehensive audit that is conducted following each election.  The purpose of this audit is to verify and confirm the accuracy of the voting system’s reported results.  A post-election tabulation audit is not a canvass or a recount; it is used to verify that the voting system accurately tallied ballots and that the winners of each contest were called correctly.

An independent, automated audit relies solely on the use of independent software to tabulate ballot images. The results from the independent tabulation are then compared to the tabulation results from the voting system. Any variances between the two tabulations are easily identified and resolved.  For the 2018 Primary Election, this office contracted with Clear Ballot, a Boston-based elections technology company which offers the ClearAudit software product. ClearAudit is the only currently available, market-ready software product that can perform an independent automated post-election tabulation audit using ballot images from another voting system.

The post-election tabulation audit is conducted using ballot images. The use of ballot images allows elections officials to maximize the technological functions of the new voting system while minimizing human error and eliminating chain of custody issues by using securely stored ballot images, rather than voted paper ballots.  The use of ballot images removes the need for election officials to physically handle or count voted ballots unless a petition for recount or other judicial challenge is granted.

A discrepancy variance level of 0.5% was established for the post-election tabulation audit1 .  If there is a variance between the voting system results and the audit results greater than 0.5% in any given contest and the variance cannot be explained, additional auditing will be performed before the election results are

Pre-Audit Tasks

To prepare for the post-election tabulation audit, SBE provided Clear Ballot with:

  • PDF files of all ballot styles for all 24 counties;
  • Pre-election reports for all precincts showing no votes cast;
  • Information to assign ballot styles to precinct; and
  • Files needed to process ballots used with the ExpressVote ballot marking device.

Upon receipt of the data, Clear Ballot:

  • Created a Ballot Definition Files for each county;
  • Validated each Ballot Definition File; and
  • Created a ClearAudit database for each county.

Audit Process

The local boards of elections send to Clear Ballot the images of ballots cast during early voting and on election day. Once Clear Ballot receives the ballot images, Clear Ballot:

  • Transfers the ballot images from each county into its corresponding audit database;
  • Tabulates the ballot images from election day and early voting;
  • Resolves unreadable ballots;
  • Performs an audit database review; and
  • Sends a Preliminary Statement of Votes Cast to SBE.

Once SBE receives the Preliminary Statement of Votes Cast, SBE provides Clear Ballot with election results from early voting and precinct-level elections results from election day.  This delay in sending the precinct-level results to Clear Ballot is intentional.  It creates a “blind” audit, meaning that Clear Ballot provides its results without knowing the results from the voting system.  Clear Ballot uses the results from early voting and election day to create various reports comparing the sets of results. 

After absentee and provisional ballots have been counted, the local boards of elections send to Clear Ballot images of counted absentee and provisional ballots.  Clear Ballot adds these ballot images into the appropriate database, tabulates these ballot images, resolves unreadable ballots, and generates a Comparison of Votes Cast for the absentee and provisional ballot canvasses.

Reports Produced by Clear Ballot

With this audit solution, election officials and other interested individuals can sort contest, ballot and precinct reports, see images of contests and ballots, and provide detailed information about how each ballot image was adjudicated. Clear Ballot produces for each county four audit reports.

  • Comparison of Cards Cast for each canvass: This report compares the number of ballots counted during early voting, on election day, during both absentee canvasses, and during the provisional canvass against the number of ballots tabulated by Clear Ballot.  This ensures that the same number of ballots were tabulated by both systems. 
  • Comparison of Ballots Cast by Precinct: This report compares the number of ballots cast in each precinct2  against the number of ballots tabulated during the audit.  This is another way to ensure that the same number of ballots are tabulated by both systems. 
  • Comparison of Votes Cast: This report compares the results from the voting system against the audit results and identifies possible discrepancies by candidate or choice. 
  • Contest Vote Discrepancy Threshold Report: This report shows - by contest - the number of vote differences between the two systems and the vote difference as a percentage. Before the audit was performed, SBE determined that a percentage of 0.5% or higher would trigger an additional review, which could include a manual review of voted paper ballots.

Reports for each county are available below or you can begin reviewing the ballots and the audit results in the web portal.

2018 Primary Election: Post-Election Tabulation Audit Reports - Phase 2 - All Ballots

2018 Primary Election: Post-Election Tabulation Audit Reports - Phase 1 - Early Voting and Election Day Ballots

1 This is calculated as the percentage of:  Absolute sum of all discrepancies in a contest
Total number of votes in a contest

2 For canvassing purposes, each early voting center is a separate “precinct.”   Each absentee canvass and provisional canvass is a separate precinct.