[EM] IRV proponents figure out how to make IRV precinct-summable

[Juho Laatu]

--- On Wed, 25/3/09, Raph Frank <raphfrk at gmail.com> wrote:

> On Wed, Mar 25, 2009 at 7:19 AM, Juho
> Laatu <juho4880 at yahoo.co.uk>
> wrote:
> > 4) To hide the individual votes for
> > privacy and security reasons. Published
> > ranked votes open up some doors for vote
> > buying and coercion. It is quite easy to
> > generate unique votes when the number of
> > candidates increases. (Also individual
> > ballots are interesting from point 1, 2
> > and 3 point of view, but dangerous.)
> 
> One option here would be to restrict the number of
> rankings.  If the
> number of voters is higher than Candidates ^ Rankings, then
> most
> possible configurations are likely to receive at least 1
> 'hit'.

Yes, that would be one approach.
One should be however careful
since although slight limitations
could have no meaningful impact
too short ballots could lead to
significant number of ballots
that didn't cover the important
preferences.

Note also that vote buying and
coercion may also tolerate
reduced probabilities. For
example a coerced voter may not
dare to vote otherwise than as
told even if there was only a
10% chance of getting caught of
voting otherwise.

With some rules one can also
generate some unusual votes. For
example in the recent Burlington
mayoral IRV election votes like
A>B>C>D=F were valid. they were
considered exhausted only if
both D and F are still in the
race when the counting reaches
those preferences in this ballot
(D or F may be a minor candidate
that certainly will be eliminated
early). this thus makes it
possible to generate unique
ballots even when all the regular
voting patterns are too common to
be used for buying/coercion.

> 
> Another option would be to do it based on the ballot
> data.  For example
> 
> 1) Start with 1 "pile" of all the ballots
> 2) Split all piles into sub-piles based on highest ranked
> difference
> 3) For each group of sub-piles (from same pile), combine
> the smallest
> sub-piles together until the smallest has at least N N (say
> 10)
> ballots,
> 4) Declare all sub-piles as piles and return to 2), unless
> no change
> was made in 3)
> 
> So, if the ballots were
> 
> 30) A>B>C
> 20) C>A>D
> 13) C>B>D
> 1) A>B>C>X>Y>Z
> 
> The process would be:
> 
> Pass 1
> Pile A>
> 30) A>B>C
> 1) A>B>C>X>Y>Z
> 
> Pile C>
> 20) C>A>D
> 13) C>B>D
> 
> Pass 2:
> Pile A>B
> 30) A>B>C
> 1) A>B>C>X>Y>Z
> 
> Pile C>A
> 20) C>A>D
> 
> Pile C>B
> 13) C>B>D
> 
> Pass 3:
> Pile A>B>C
> 30) A>B>C
> 1) A>B>C>X>Y>Z
> 
> Pile C>A>D
> 20) C>A>D
> 
> Pile C>B>D
> 13) C>B>D
> 
> Pass 3:
> Sub-Pile A>B>C
> 30) A>B>C
> 
> Sub-Pile A>B>C>X
> 1) A>B>C>X>Y>Z
> 
> Pile C>A>D
> 20) C>A>D
> 
> Pile C>B>D
> 13) C>B>D
> 
> Sub-pile A>B>C>X hasn't enough ballots, so is
> combined with the next
> lowest sub-pile, A>B>C
> 
> Pile A>B>C
> 30) A>B>C
> 1) A>B>C>X>Y>Z
> 
> Pile C>A>D
> 20) C>A>D
> 
> Pile C>B>D
> 13) C>B>D
> 
> No change has occured, so end.
> 
> The results would be declared as
> 
> 31) A>B>C
> 20) C>A>D
> 13) C>B>D
> 
> This gives a loss of accuracy, but hopefully not to much.
> 
> Also, it doesn't work if you are providing ballot images.

Yes, ballot images and
requirement of secret
votes is a bad mix.

> 
> > In summary, maybe raw digitized ballots
> > are good enough in most cases for the
> > computers, but humans may need more
> > compact information (not necessarily
> > summable) for various reasons.
> 
> The theory was that the ballots would be published and
> non-profit/bored programmers could convert them into
> rankings.
> 
> The government would publish a block of ballots and their
> associated
> official rankings.
> 
> If there was errors, it would be possible for them to
> provide a series
> of links to offical ballot/rankings pairs which clearly
> don't match
> what is actually on the image.
> 
> > The
> > privacy point may set requirements on
> > what to publish and what not (some
> > countries are already now quite strict
> > on this).
> 
> You could have a rule that a ballot is only valid if it
> doesn't have
> marks.

This must be a common practice
in many places.

Juho


>  Also, ballots images could have parts of the
> image censored,
> to cover up those marks.  Ofc, the actual boxes where
> the person
> indicates the rankings would have to be shown.
> 
> This somewhat goes against the principle of multiple
> independent
> groups imaging the ballots for comparison to the official
> list.  In
> principle, you could require that they mask off all parts
> of the image
> other than the ranking boxes and the ballot ID number.
> 
> I guess it depends on the lengths people would go to. 
> In principle,
> you could require that the seller use a special font when
> filling in
> their ballot.
>