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

[Juho Laatu]

--- On Wed, 25/3/09, Jonathan Lundell <jlundell at pobox.com> wrote:

> Lam wrote:
> 
> > IRV can be made sort of summable:
> > 
> > <http://lists.electorama.com/htdig.cgi/election-methods-electorama.com/2001-September/006595.html>
> > 
> > Buddha Buck replied with an IRV example that much more
> clearly explained
> > the method:
> > 
> > <http://lists..electorama.com/htdig.cgi/election-methods-electorama.com/2001-September/006598.html>
> > 
> > Quite neat I think.
> 
> Yes, but...what's the point? That is, what problem are you
> trying to solve, exactly?
> 
> If you're in a position to compute the matrix, why not
> simply send the file of ballot data? It's not as if it's
> going to be prohibitively large. The 2008 US Presidential
> election had ~13 million votes in California, the largest
> state. Ten candidates at a byte per candidate would only be
> order of a 100MB for the entire state, before compression.
> Heck, I've got mp3's bigger than that.

Yes, good question. IRV votes thus don't
take excessive amount of space and can be
compressed and can be summed up (although
not very compactly).

Possible answers might include:

1) To help verifying the vote counting
process. If the partial results are
counted/verified already locally it may
be more difficult to falsify the results.
With the modern personal computers it is
however also possible to anyone to collect
all the <100MB files in one's own computer
and verify the election if all the
districts publish their ballots.

2) To build trust on the system by
showing the partial results to people.
In this case the summed partial results
should be very simple so that every
regular voter can see that they are ok.
A Condorcet pairwise comparison matrix
might be too difficult. Sum of votes per
each candidate could be simple enough.
Also publishing the outcome of the
election based on the votes of one
district alone can help (although these
results would not be further used /
usable when summing up the results).
This is easy enough for all methods.
And the voters will see if the results
are credible, not e.g. opposite to what
everyone expected.

3) For general interest. The local
results in point 2 above are certainly
interesting. One must be capable of
summing up the results so that one can
see what happened. Also this case does
not set a requirement of reusing these
"summed up" results later in the process
when the election wide results are
counted (raw ballot data will do).
(Also the Condorcet pairwise matrix may
be very interesting material to study
and speculate on.)

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.)

5) To distribute the load of vote
counting and to speed up the process.
This mostly applies to hand counting.
In the time of computers it may be
enough to just digitize the votes
locally (unless already digital) and
to verify these transformations.

6) To keep possible recounts local. This
is also mainly related to hand counting.
Nowadays local re-digitization may often
be enough..

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
privacy point may set requirements on
what to publish and what not (some
countries are already now quite strict
on this). In IRV there may thus be a
need to keep the ballots hidden or to
break them in such a way that individual
ballots can not be recognized (or
verified to the buyer/coercer).

Juho