Re: TAR--audits. urgently need help to get law.

From: Ron Crane <voting_at_lastland_dot_net>
Date: Tue Nov 21 2006 - 13:35:49 CST

Charlie Strauss wrote:
> Kurt, (or anyone). I urgently need your help turing the Targeted
> Audit Recount into law.
> In New mexico were writing a law to introduce more rigorous recount
> procedures. The current bill is enclosed.
> But we just got the invitiation to include a Targeted Audit in to the
> bill by the subcommittee who will be recommending the bill but we have
> to get the amendments in by tomorrow (friday).
> First is there any attempts to write TAR as legislation alraedy available?
> Second TAR has one very serious problem that is keeping me from
> finishing this amendment.
> Unlike a randomly sampled recount, you can't rigorously use the
> results of a TAR to estimate how many machines are making errors. If
> you can estimate how many machines in the full population are making
> errors then you can construct a resonable argument about how likely it
> is that there could be enough errors in the election to change it's
> outcome based on the sample. From that you can either iteratively
> augment the sample size or decide a full recount is needed.
I am sorry that I didn't get to this before the deadline, but I hope
that my response might help your efforts generally.

I think that TAR precincts, on average, are about as likely to exhibit
tampering as randomly-chosen precincts (I don't have much faith in
candidates' and parties' analyses of tampering patterns). This suggests
treating the TAR precincts as if they had been chosen randomly. If TAR
precincts turn out to exhibit tampering more often than randomly-chosen
precincts, this approach oversamples the vote, which isn't a bad thing.
If TAR precincts exhibit tampering less often than randomly-chosen
precincts, this approach undersamples the vote, which is why you want
TAR to supplement, not to replace, random sampling.

Of course, recounting pure DREs is essentially meaningless, and
recounting VVPATs is probably not very useful because few voters
generally check them. The Brennan Center's report cited a study by Ted
Selker showing <3% error-detection rate in an (admittedly synthetic)
study. We need to take account of the VVPAT error-detection rate if
VVPAT recounts are to have any real meaning. [1]
> The basic law simply says this:
> enough machines will be sampled (hand counted) such that there is a
> 90% chance of detecting whether an election outcome would be reversed
> by bad machines. ("machine" here means precinct-machine-equivalents:
> batch counted absentee ballots are divided into sub-batches of the
> size of a typical precinct ballot count). If a mismatch between the
> hand count and the electronic count is found then an election
> commission will decide how to expand the recount: their criteria is
> to keep expanding until they estimate their is less than a 10% chance
> the election would be reversed.
I think 90% is too low. Elections are among the most important things we
do. Even an iPod has something like three-9s reliability (it will work
99.9% of the time). True, inevitable errors limit hand recounts'
accuracy, but we should strive for something better than a 90% chance of
detecting tampering. The Brennan Center's report seemed to suggest 95%.


[1] We also need to account for the possibility that presentation
attacks (e.g., dropping candidates from the ballot, reordering the
ballot) will influence some voters actually to change their votes to the
ones a tamperer prefers. Alas, VVPAT doesn't help detect these attacks.
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Received on Thu Nov 30 23:17:10 2006

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