[EM] STV and weighted positional methods

[Raph Frank]

On Sat, Jan 31, 2009 at 7:47 PM, Kathy Dopp <kathy.dopp at gmail.com> wrote:
> On Sat, Jan 31, 2009 at 12:03 PM, Raph Frank <raphfrk at gmail.com> wrote:
>
>>> Again what is your view on condorcet methods and approval?
>
> Obviously most other voting methods, approval, range, condorcet, etc.
> are worlds superior to IRV/STV because they are precinct-summable,
> monotonic, and treat all ballots equally.  Almost any method that has
> been proposed is far far superior, more equitable, and fairer than
> IRV/STV.

Well, I would disagree that plurality is better than IRV.  IRV is
slightly better (or at worse, they are both equally bad).

I think that there are lots of methods that are better than both
plurality and IRV, like approval and condorcet methods.

Also, I think  PR-STV is one of the best multi-seat PR methods.  I
think the benefits of PR-STV in terms of giving the voters maximum
power, outweigh non-monotonic effects.

What would be your view of single non-transferable vote?  This is the
method where each voter votes for one candidate and the N candidates
with the highest vote are elected.  This is the multi-winner version
of plurality.

Actually, even if surplus transfers were performed, it would still be
monotonic (your vote would always go to your top ranked candidate
unless he is elected).  It is only the elimination part of PR-STV that
causes the non-monotonic effects.

In IRV, voting for your favourite might case your 2nd favourite to be
eliminated and then your favourite loses in the last round to your
least favourite.

> False statement. My vote will either have a 100% chance of helping my
> first choice candidate or a 100% chance of hurting my first choice
> candidate, depending on how all other voters vote, which I cannot tell
> without being God, which most voters are not.  So I have no way when
> voting of knowing for certain how to vote to help my favorite
> candidate win. Should I rank my favorite first, last or not at all to
> help him? No way to know.

Well, I guess it depends on what you know.  Prior to the election, you
don't know the effect of each possible vote you could cast.  After the
election, you could work out if your vote backfired.  However, in
almost all cases, it would turn out that the winning margin was more
than 1 vote, anyway.

I think in practice, the situation would be that there are 2 major
party candidates and lots of small parties.

In that situation, you would be pretty safe voting honestly, just make
sure you rank one of the top 2 somewhere on your ballot.  The small
party candidates will be eliminated first and then the last round will
be between the 2 contenders (or one of the top-2 will pass the 50%
threshold before the last round).

IRV doesn't handle a situation where there are 3 front-runners very
well.  In that case, there is no easy way to know how to vote.