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

From: Ron Crane <voting_at_lastland_dot_net>
Date: Tue Nov 21 2006 - 21:30:45 CST
charlie strauss wrote...

1/4 was chosen so that we could treat the tar machines as though they were randomly chosen without excessively dilluting the statistical power of the random sample. That is it will introduce a slight bias but not  one big enough to argue over. Most of the time it weel serves  It's main purpose: to satisfy the the candidates that anomlies were simply anomlous not errors.

in typical elections the number of recounted machines in NM will be small: if the election margin between 2 candidates was 2% then to achieve 90% confidence all of NM would have to count 33 machines. 
Which formula did you use to calculate this number?

ANSWER:   Don't worry.  Don't have the formula off hand, but this is pretty easy mathematics. (By the way the original calculation was done by people who compute reliability statistics for Nuclear weapons assurance)
This isn't sufficient. We are all here because we worry about these things. I am quite sure that the appropriate formula is not "pretty easy mathematics," since Kathy Dopp and others spent considerable effort deriving it just this past summer, and, in the end, I believe that they could not find a closed-form solution. Did you use Dopp's spreadsheet? How is the calculation written into the proposed legislation? Can we see the entire bill?


 Thus the number in the TAR is very small.  So we felt it was best to place the choice in the hands of the major stakeholder parties rather than candidates. This way we get party wide buy-in to the entire recount process both random and TAR, and thus a more generally authoritative public reassurance (parties we felt are likely to be more restrained about unsupported accusations than individual candidates).  The SOS's share is there to help cover the independent and minor parties interests as well as to target known problem spots that might not be of interest to the parties.

If the sample detects a bad machine the problem is handed over a commission to decide how to expand the recount give whatever error modality was detected.  (e.g. in some case the errors will point to a county specific or precinct specific, problem not a statewide, or vica vera)  They are charged with expanding the recount sample until it is determined that there less than 10% chance any race would be overturned.

  
Are they told how to determine the size and location of the recount sample?

They are told how they can go about getting help on answering it. 
This approach gives the commission considerable discretion. If you know the appropriate formula, the legislation should contain it. That doesn't mean you should try to codify everything, but you should try to codify important things whose correctness you know.

In this second stage, where a detection event has occurred,  it's more important to maximize the statistical power of the sample to estimate the error size accurately rather than search for more events.  Therefore, we made it discresionary whether to include targeted precints in the expansion.

When I say machines and recount what this means is a recount of the paper ballots by hand from a given machine.


Some of The reasons we are comfortable with 90% here is that 1) we feel that in the case of systematic errors that in many cases there will either be none or legislative district wide errors.   The latter will always exceed the 90% threshold level.  
If indeed we're talking about innocent errors, then probably yes.
2) Moreover, remember that the number we chose to recount is based on the closest race.  
So you recount all races on all ballots that include the closest race? Do the detection-expansion thresholds then apply to all of those races?
Thus even if the detection probability for that race is 90% it's far higher for all the other races.  It's not particularly likely that an error would only affect the closest race.  3) The same logic applies to fraud being detected at greater than 90% confidence. 
I don't agree with sentence (3). It is pretty likely that fraud will be directed at one or a few races, rather than being spread across the entire ballot.

Answer: Yes, that's my point: fraud might be focused on some single  race.  But the fraudster cannot be assured that race will be the one that sets the recount threshold.  There might be a tighter race than the one she planned to rig.

To verify, you recount all races on all ballots that include the closest race?

4) And we also feel that if the recount deters fraudsters then there's little different in deterence between 90% and 99%.
Attackers implicitly weigh (expected rewards * expected likelihood of getting rewards) against (expected penalties * expected likelihood of being penalized). I wonder whether a 90% detection threshold will be enough to deter attackers who see huge rewards in success and see little chance of being caught. Considering that the number of machines you need to recount for 90% is so small, why not consider raising the threshold to 95% (as the Brennan Center implicitly recommended) and seeing whether the recount is still manageable?

ANSWER: No attackers won't be weighing those so carefully. Otherwise we'd not have so many crimminals.  People are terrible at cost beneift analysis. Costs matter to the legislature.  It's one of the first questions asked always.  Going from 90 to 99% roughly doubles the number of machines needed for an audit and that's roughly double the cost.  THe real question is do you want 90% or none at all?
90% is better than none at all, if those really all the only choices. But 90% is not enough, and your first three sentences support this point. Is the legislature really concerned about the cost difference between recounting 33 machines (from your original message) and 66?

-R

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Received on Thu Nov 30 23:17:10 2006

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