Voting Project Needs Python People

Alan Dechert adechert at earthlink.net
Wed Jul 23 21:08:12 CEST 2003


"Andrew Dalke" <adalke at mindspring.com> wrote in message
news:bfkch9$is4$1 at slb4.atl.mindspring.net...
> Alan Dechert:
> > catch it.  If one percent of the electronic votes were altered (evenly
> > distributed), you will find one mismatch for sure after checking only a
> > dozen or two ballots.
>
> Actually, around 70 ballots.
>
> The odds of finding one ballot to be wrong is 1%, so there's a 99%
> chance that it's unaltered.  There's a 0.99*0.99 chance that two are
> unaltered, and in general a 0.99**n chance that n are unaltered.
>
> To get even odds of noticing an error requires
>
>   0.99**n == 0.5
>   --> log(0.99)*n == log(0.5)
>
> >>> math.log(0.5) / math.log(0.99)
> 68.967563936528421
> >>>
>
> about 70 verifications.
>
 A likely story.  I actually took combinatorics and a class in statistics in
college.  But that was a long time ago.  Since then, many brain cells have
died, tragically.

BTW, do you know about cumulative binomial distribution?  I think we need to
include a tool like this to give us some "C.L" (confidence level) short of
verifying that every single paper ballot matches its electronic counterpart.

http://www.reliasoft.com/newsletter/2q2001/cumulative_binomial.htm

What I really want is a calculator.  Do you know of a free calculator for
this?  If not, could you make one? (for free, of course).

Alan Dechert






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