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ES&S Opti-Scan Machines Found Miscounting By 4%

ES&S Opti-Scans Found Miscounting by 4% (8% margin-swing)

Dear Friends,

I do not have all the details, but this story needs immediate investigation before calling winners tomorrow in any state using ES&S M-100s to count its votes whenever the reported margin is closer than 8%.

The paper ballot precinct-based optical scan voting system used in a large proportion of US jurisdictions is producing wildly inaccurate counts of ballots that are off by as much as 4% per precinct - thus altering the vote margin possibly by as much as 8% by shifting votes from one candidate to another - depending on how the errors occur.

The ES&S M100 is used in at least some or all counties in the following states: AL, AR, AZ, CA, CO, FL, IA, IL, IN, KS, ME, MI, MN, MO, MS, MT, NC, ND, NE, NM, OH, PA, RI, SD,TN, TX, VA, WA, WI, WV, and WY.

The story, with links and copies of at least one original document is forwarded in the email below.

Voter marked paper ballots, even if the machines that count them are inaccurate, are more auditable because accurate vote counts can always be recovered by hand-counting the paper ballots, unlike with touchscreen voting systems, but machine counts are not to be blindly trusted - and this is a good example why not. It is easier to detect errors produced by paper ballot optiscal-scan systems than by touchscreen e-ballot systems.

The usage distribution of the ES&S M-100 scanners in the U.S. can be found here:

This is yet another reason why States should be conducting routine independent manual post-election audits like those described in this proposal: How to Audit Election Outcome Accuracy

---------- Forwarded message ---------- From: Strauss charlie Date: Mon, Nov 3, 2008 at 9:19 PM Subject: ES&S opscans found miscounting by 4% To: Verfied NM Voting

There has been a grave concern raised about the accuracy of ES&S M-100 opscans (ES&S's primary precinct model) raised 10 days ago.

A Michigan Clerk wrote to the (federal-ish) Election Assistance Commission on october 24 to tell them she has been given a substantial reason to doubt their accuracy. In Logic and Accuracy testing for the the clerk reports that some of her Communities reported "the same ballots run through the same machines, yielded different results each time"

How big was the error? Wired extends the story:

"According to news stories, a race in the August Republican primary in one Michigan township did have a discrepancy in tallies that were counted by hand and by ES&S optical-scan machines. The clerks race in Plymouth Township was recounted after the losing candidate requested it. The initial machine count had showed Joe Bridgman defeating Mary Ann Prchlik by 1,920 to 1,170. But the hand count ( - narrowed the margin to 1,885 to 1,727."

That is, the totals shifted nearly 4% of one candidates 1170 votes to his opponent: that reduced the margin of victory in that township by 8%!! (a very uncomfortable error)

It was both ironic and especially disconcerting since that the race in question was for the township's clerk and the winning candidate was the Deputy Clerk.

Note that this is one township. And also note that the L&A tests were off in 4% of the communities running the L&A tests. It does not report how many machines in each community failed, but if follows the common pattern their probably is 1 or at most 2 machines in a typical precinct. So the impact on statewide raises is presumably somewhat damped over the impact on local races but is still absurdly large.

Conversely, the problem is attributed to dust buildup blocking the sensors and possibly interfering with the electronics. The concern is that the next election is going to dwarf the past one in the amount of dust generated.

"In Oakland county when officials there met with ES&S to discuss the errors encountered during logic and accuracy testing, ES&S maintained that the problem was dust and debris build-up on the sensors inside the machines.

"This has impacted the Digital to Analog Converter (DAC) settings for the two Contact Image Sensors (CIS)," Johnson wrote the EAC."

Now presumbaly, a lot of the dust comes from the kind of ballot stock used so we don't know if this will occur nationwide. But since these are spec-ed by ES&S it's plausible that this will be ubiquitous.

Like NM, Michigan also is forbidden from doing their own "cleaning" by ES&S on pain of voiding the warrantee (and possibly the certification).

I have advocated before that NM urgently needs to get a larger IT staff in the SOS office to get this situation under control. NM needs to have a credible staffing level in part to give it leverage to renegotiate these maintenance contracts that are bankrupting the clerks, or causing them not to maintain machines.


------------------- forwarded by

Kathy Dopp

The material expressed herein is the informed product of the author's fact-finding and investigative efforts. Dopp is a Mathematician, Expert in election audit mathematics and procedures; in exit poll discrepancy analysis; and can be reached at

P.O. Box 680192 Park City, UT 84068 phone 435-658-4657

How to Audit Election Outcome Accuracy

History of Confidence Election Auditing Development & Overview of Election Auditing Fundamentals

Voters Have Reason to Worry


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