[E-voting] The VVAT Debate - Technical or Not ?

Michael McMahon michael at hexmedia.com
Thu Mar 11 18:13:01 GMT 2004

Your message was sent on Tuesday, but I only just got it now.
Same for a lot of other messages over last two days. I don't know
what's happening.

Patrick O'Beirne wrote:

> At 14:07 09/03/2004, Michael McMahon wrote:
>> There is also the issue of effective sample sizes. You can't take a 
>> sample
>> from an individual (constituency) election. At this level, auditing 
>> has to be all or nothing.
> I think that depends on what you are trying to detect by sampling. If 
> you require a 100% guarantee that you will not miss ANY error, you 
> must have 100% checking.  A 99.997% assurance might be obtained by a 
> 10% sample (SWAG, don't take that as serious), depending on all the 
> other things. The choice of 99.997% or 99% or 95% or whatever is a 
> political decision I suppose .. unless some voting experts know how 
> much uncertainty is accepted in the present system,
My original point was that a 10% sample of a single set of election 
ballots is no use, because there
is nothing to check it against. You can't correlate a sample of 
electronic ballots to the paper
ballots they correspond to, because no such correspondance exists. 
However, some have argued
that it is possible to identify voters from their preferences, so maybe 
sampling at some
value less than 100% is feasible.

The point that started off this whole discussion was that the Chaum 
system performs an electronic
audit within individual (constituency) elections to a high level of 
accuracy, and in my opinion
at least, VVATs would be a useful safety net, that would only *have* to 
be used in exceptional
cases, such as when the Chaum audit fails.

But I fully accept that a VVAT audit (even at 100% checking) is nothing 
like as complicated
as the present manual count. It is easy to imagine how it could be done, 
quite efficiently
with computer assistance.


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