Abd Ul,
from the data you produce, I agree that for the Burlington election, IRV
did produce the same result
FPTP would have produced.
However, nobody can generalize this perticular case to any election.
I agree that in non-partisan election the rallying pattern of defeated
voters does not fit only one typical set of preferences.
However again, a statistical analysis of general preferences shows an
unbalance of preferences, even for non-partisan elections.
Is this unbalance major to the point that IRV could allow a come-back
from another candidate than the plurality winner, or
is this unbalance minor so IRV does not change anything, it depends of
each election.
On a last aspect, I do agree that Condorcet is better than both. And I
admit that , even if I believe that the distribution
of a generalized set of preferences is unbalanced, I have not yet been
able to evaluate or quantify this unbalance.
You can argue that as long that I was not able to quantify by how much
this unbalance occurs (amplitude distribution), it is not
acceptable to claim that this unbalance should allow IRV to find a
"better" winner. But, we do have data of previous elections and
because we both agree that a Condorcet winner is a "better" winner for
this purpose, we can use this reference to evaluate the
combined impact of IRV and the unbalance of the preference sets. Thus,
even if I do dot know the general unbalance distribution,
I can observe that IRV allows more often to obtain a Condoret winner
when plurality fails, than plurality finds a Condorcet winner
when IRV fails. So I claim IRV is more reliable than plurality.
Yours, Stéphane.
Abd ul-Rahman Lomax a écrit :
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....
----
Election-Methods mailing list - see http://electorama.com/em for list
info
----
Election-Methods mailing list - see http://electorama.com/em for list info
