[EM] Satisfaction Approval Voting - A Better Proportional Representation Electoral Method

Jameson Quinn jameson.quinn at gmail.com
Wed May 19 20:37:17 PDT 2010


If you're looking for simple proportional systems, you could look at "total
representation", where district-based representatives win with a majority,
but some extra seats are assigned to the highest-vote-getting losers of
underrepresented parties to help balance.

I believe that SAV is not that great a system. It requires too much strategy
from the voters; you have to know how many voters like you there are in
order to know how much to split up your vote. A faction which spread its
vote to thin could end up entirely unrepresented - even if it were a
majority faction.

I would propose SPA (Summable Proportional Approval) voting.

1. Each voter votes an approval ballot. It is easy to vote either a "party
ballot", a "modified party ballot" with extra approvals or disapprovals, or
a "combined party ballot" which approves of two or more parties.
2. Each ballot is converted to two matrices
  a) one with candidate approvals on the diagonal and candidate correlations
on the off-diagonal
  b) one with number-of-votes-per-candidate on the columns and candidates on
the rows
3. The two matrices are added for all ballots.
4. The highest candidate total is elected, and a droop quota is deducted
from their total. The matrices are used to deduct from the totals of other
candidates with a high correlation. Explaining the process in words is very
longwinded; soon I will post a working source code version which implements
this process, and prove that it's proportional.
5. Repeat 4 until you've elected enough candidates.

The math is complicated. However, it's only to make the process summable,
and thus to make recounts verifiable. If you don't need summability, you
just reweight the individual ballots to deduct a Droop quota, which is
trivial mathematically.

JQ

2010/5/19 Kathy Dopp <kathy.dopp at gmail.com>

> One of the authors of the Satisfaction Approval Voting paper responded
> to your comments, which I'd forwarded to them:
>
> "I consider it [SAV] a very simple system--comparable to approval
> voting--and to fix its alleged flaws would, in my opinion,
> considerably complicate it without necessarily producing a better
> result (however this is defined)."
>
> I tend to agree, although I've not studied the issue enough to be 100%
> certain.  There is a lot to be said for simplicity, additive feature,
> compatibility with existing voting systems and ballots, auditability,
> understandability, etc.
>
> So far, I think I would recommend both SAV and the party list system
> as proportional representation systems but am open to finding others
> too.
>
> Kathy
>
> On Wed, May 19, 2010 at 7:21 PM, Kristofer Munsterhjelm
> <km-elmet at broadpark.no> wrote:
> > Kristofer Munsterhjelm wrote:
> >
> >> Now, you may say that the second problem is analogous to STV's Woodall
> >> vote management (don't vote for a candidate that would otherwise win),
> >
> > I meant, of course, Hylland vote management. Woodall vote management
> > involves prefixing the vote with preferences for no-hopes, and as such
> isn't
> > relevant in this context.
> >
>
>
>
> --
>
> Kathy Dopp
> http://electionmathematics.org
> Town of Colonie, NY 12304
> "One of the best ways to keep any conversation civil is to support the
> discussion with true facts."
>
> Realities Mar Instant Runoff Voting
>
> http://electionmathematics.org/ucvAnalysis/US/RCV-IRV/InstantRunoffVotingFlaws.pdf
>
> Voters Have Reason to Worry
> http://utahcountvotes.org/UT/UtahCountVotes-ThadHall-Response.pdf
>
> View my research on my SSRN Author page:
> http://ssrn.com/author=1451051
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
>
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