At 09:23 AM 1/8/2010, Stéphane Rouillon wrote:
> Therefore IRV/STV is no better than plurality, but has extra very
> serious flaws, inequities, and vagaries that plurality does not have.
I definitively disagree. Plurality is worst than IRV.
The flaws that IRV does have are real.
But these problems appear very less often than
the splitting-vote issue of FPTP.
Stephane, as to abstract theoretical voting
systems, naively analyzed, and also as to certain
real-world situations -- but not others -- you'd
be correct. But notice that Kathy Dopp claimed
that IRV is "no better than plurality." That's
because, in nonpartisan elections, it appears
that IRV closely reproduces the results of
plurality. We have tended to think in terms of
neat factions, arranged in a spectrum, so that
you can predict vote transfer patterns with IRV,
but nonpartisan elections don't work that way.
Generally, in nonpartisan elections in the U.S.,
vote transfers with IRV do not alter the
preference order among the remaining candidates.
Exceptions may occur when races are very close.
On the other hand, in one-third of nonpartisan
top-two runoff elections, which IRV supposedly
simulates, the runner-up in the primary goes on
to win the runoff, a "comeback election,"
according to a FairVote study. It simply does not happen with IRV.
If you have top-two runoff as a system in use,
and you replace it with IRV, for nonpartisan
elections, you might as well replace it with
plurality, you will get the same results. That's what is being said.
The recent election in Burlington, Vermont,
though, was a partisan election. There, Kiss was
trailing Wright in first-preference votes, but
Kiss obtained enough vote transfers from Montrose
supporters to pass up Wright in the second round
of counting. Kiss is Progressive, Wright
Republican, and Montrose is a Democrat.
But looking at the actual voting data, which is
available, we can see that Montrose was, in fact,
the Condorcet winner, and, as it's been pointed
out, had a few of the Write supporters voted for
Montrose in first place instead of in second,
Montrose would have won. In other words, IRV will
punish you (as does plurality) for voting your
conscience; but with Plurality, it's obvious and
everyone would know that voting for a Republican
in Burlington would be a wasted vote (where the
leading party is Progressive), so they'd have
compromised and voted accordingly and Montrose would quite likely have won.
Also, there is good reason to believe that most
voters would vote according to the same patterns
if the method were Bucklin. The ballot would have
been the same, three-rank. With Bucklin, first
round results would have been same as IRV,
presumably (and assuming that nobody did, with
IRV, vote strategically already, we can assume
that with the limited experience with IRV, few
would have known to do so). Data is from a quite
good video Kathy Dopp pointed to, http://www.youtube.com/watch?v=bPCS-zWuel8
candidate 1st 2nd
Montrose 2554 3556
Kiss 2982 1827
Wright 3297 1138
------------------------------
8843 6521
The ballots show third rank data, but my view is
that this isn't meaningful, many voters may
actually be thinking that they are voting
*against* a candidate by ranking in third place.
(There were other minor candidates on the ballot
and the data in the video is obviously
oversimplified, but it serves as an example.)
As you can see, no candidate gained a majority in
first preference. There is serious vote-splitting
between Montrose and Kiss, quite likely. With
IRV, Montrose is eliminated before the second
rank votes for him are counted. That's 3556 votes that weren't counted!
With Bucklin, all the votes are counted up to the
ranks necessary to find a majority. The majority
is 4422. Adding in the second rank votes, we get
Montrose 6110
Kiss 4809
Wright 4435
It's not even close! Montrose is the first or
second choice of roughly three-fourths of the
voters. This is Bucklin voting, supremely easy to
count, just add up the expressed preferences at
each rank. It's Instant Runoff Approval.
It's true that there might not be such heavy
usage of second rank with Bucklin (though already
2312 voters "truncated," not expressing a second
preference). However, there are two possible ways to use Bucklin.
We can generally assume that the votes in the
Burlington election were sincere. They might not
stay that way if Burlington Republican voters
realize they've been had. Because there are no
candidate eliminations in Bucklin, though,
supporters of minor candidates can safely vote
their conscience in first rank, because their
vote will either help their candidate win
(unlikely by the conditions) or will cause
majority failure or will be moot in any case.
There is no need for Favorite Betrayal, as it's called.
What we have in Burlinton is a three party
system, with the Republicans being, slightly, the
largest. Naturally, they might prefer Plurality,
except that they know they won't win, because
they'd need more than a third of the voters. I'd
expect Burlington to see a lot of runoffs if top-two runoff is used, straight.
But consider top-two runoff with Bucklin used in
the primary (and I believe that it would be wise
to allow write-ins in the runoff and use Bucklin
there too to prevent the spoiler effect).
The voters would have -- would learn that they
have -- a choice: add second rank (or third rank)
votes if you approve of additional candidates,
even though you have some stronger preference, or
see a runoff election. The circumstances actually
encourage a form of range voting, whether or not
you'd add a second or third rank vote depends on
*how much* you prefer your favorite over the
others. This would amalgamate to show average
preference strength against an actual
inconvenience. In Bucklin, it's true, if your
favorite doesn't win in the first round, your
second rank vote can cause your favorite to lose.
IRV allows you to think you are avoiding this
possibly undesirable outcome, but only because it
takes your candidate and eliminates him.
Were the Wright voters in Burlington happy
because their vote for Wright was "protected" from "hurting" Wright?
The 2009 Burlington outcome was truly outrageous,
and the votes show it. It was a classic center
squeeze situation, and the possibility of this is
precisely why Robert's Rules of Order criticizes
IRV and considers true repeated balloting
(without eliminations!) superior. RRO doesn't
consider other forms of preferential voting
though it notes that they exist. I understand
that this is because RRO is a manual of actual
practice, not of theoretical recommendations, but
there are much, much better voting systems.
Bucklin, to me, has these advantages:
1. It's been widely used in the U.S., about
eighty years ago. It was very popular, and much
more widely used than the current IRV fad. Why
was it dumped? Good question. I wish I knew. Most
likely answer: it worked, and some people didn't
like that, such as the Minnesota Supreme Court.
2. It's cheap to canvass. Just add up votes, no
complicated handling, totals can be summed by precinct easily and transmitted.
3. It preserves the ability to vote for more than
one candidate but simultaneously indicate
preference, unlike Approval. (Bucklin is really
Approval voting with a "virtual runoff" feature,
so that approvals are added in as needed.)
4. It satisfies the Majority Criterion, which is
politically desirable. It does not satisfy,
technically, the Condorcet Criterion, though my
sense is that Condorcet failure would be rare and with low preference strength.
Bucklin would have allowed the Republican voters
in Burlington to vote for Wright without
suffering the consequential loss of their second
choice to their lowest preference. Someone should tell them!
I think it's worth looking at how voting strategy
might work. Some candidates might encourage their
supporters not to add lower ranked votes for
their major opponent. But we already see that
many of the voters in Burlington did not vote the
standard politically predictable patterns. We had
some Wright supporters voting second rank for
Kiss. Did that mean that they really preferred
Kiss to Montrose. Maybe. Or they believed that
this would somehow help Wright. Likewise, we had
Kiss voters voting second rank for Wright. But in
both cases these numbers were fairly small.
I would indeed expect truncation to increase a
bit with Bucklin, maybe even a lot. However, not
enough, I'm practically certain, to alter the
result. Second rank voting would have had to
decline by 1689 votes for Montrose not to gain a
majority, from his 3556 second-rank votes as
shown. He'd still have a plurality. If a majority
were required, he'd be in the runoff, certainly
(whereas with a vote-for-one primary, he might be eliminated).
If runoffs are held when there is majority
failure, voters should know that they should not
vote for a candidate, at any rank, unless they
prefer the election of that candidate to a runoff
being held (with its costs, inconvenience, and
risks). Voters should also be able to leave lower
ranks blank, deferring the counting of a lower
ranked vote until later in the process. (It's a
little more protection against "harming your
favorite.") They should also be able to vote for
more than one candidate at any rank, for reasons
I won't explain here, but it is a good strategy
if you really don't have a strong preference
between two candidates. But, of course, they
should never be able to vote more than once for
any given candidate, should they mark the same
candidate in lower ranks, those additional marks
would simply be disregarded, they should not
invalidate the ballot. A vote for a candidate
will be counted at the highest rank expressed....
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