Here it is noted that IRV has a black mark for failing to correctly award W
as deserving winner. They seem not to notice that IRV's failure is also
describable as incorrectly discarding W as an undeserving loser.
As to escaping two party domination, think on:
Plurality: If I prefer one of their candidates over the other, I must vote
my preference between them, and wait til next time to think of voting for a
minor party candidate.
Approval: Here I can vote for both a major and a minor, but must vote as
if equally desiring the barely tolerable major over the much better minor.
IRV: See above.
Condorcet: Can use IRV ballots and voting, but Condorcet promises to read
all that I vote on them. Further, its N*N array is a useful record as to
relative strength of candidates/parties.
And "center-squeeze effect" or "Center-pull"? Makes sense if there is only
one issue of interest for an election. Makes less sense when, as usually
happens, there are multiple important issues with each major party doing
better at satisfying each voter on part of the issues.
DWK
On Tue, 20 Jan 2009 05:10:50 -0000 baring001 wrote:
Tom,
The problem is that the center-squeeze effect can easily keep a center
candidate from reaching 20 percent of the vote.
Of course the more basic problem is that IRV uses plurality to decide
which candidates to eliminate. If plurality can't be trusted to pick
the winner, why would we expect it to reliably pick losers so that we
can somehow "back into" finding a winner?
In over 10 years of following election reform, I still haven't seen a
good argument for anything more complicated than approval voting.
If you must insist on elimination rounds, the best method would be to
conduct an approval vote and then during the vote tally iteratively
eliminate candidates with the fewest approvals.
Short of that, plurality could be called a "good enough" system. It's
just that if you're not happy with the two parties' nominees, your
best recourse is to join one party and attempt to change it from within.
--- In [email protected], "Tom Ruen"
<tomr...@...> wrote:
Baring01,
I'd support using IRV as an "elimination process" rather than picking a
winner. That is, eliminate one candidate at a time from the bottom
until all
remaining candidates have at least 20% of the vote. THEN see if a
Condorcet
winner exists. If none, then randomly pick a winner from the Smith
Set (The
smallest set of candidates who can defeat all candidates outside the
set
head-to-head.)
I think this handles the "Center-squeeze" you describe AND handles an
opposite problem of a perhaps called "Center-pull" of a pure Condorcet
method where a center candidate gains power merely by being cautiously
inoffense to all sides.
Well, this IRV-Condorcet Hybrid system is my favorite, although in
practice,
I continue to believe Plurality is the real enemy and its silly to
argue
about minor differences in majority systems.
IRV is "good enough" in practice, and perhaps best, encouraging
candidates
and voters to "agree to agree" before the election (like the
plurality) due
to spoiler fears, and that pre-election organization is what helps
keep the
number of candidates managable for voters!
Plurality rewards a "two party system", and IRV/runoffs rewards "the
two
strongest candidates" who may not always be from the same two may
parties in
different elections.
Tom Ruen
----- Original Message -----
From: "baring001" <baring...@...>
To: <[email protected]>
Sent: Thursday, January 08, 2009 10:22 AM
Subject: [IRV-freewheeling] Simple illustration of center-squeeze
effect in
runoff voting
For a simple illustration of the center-squeeze effect, imagine a
three-way race in which the electorate is uniformly distributed across
some policy continuum. Candidates A, B, and C are positioned at the
top edge of the 25th, 50th, and 75th percentiles, respectively.
If the voters rank their choices in order of closeness on this
continuum, then voters from 1st to 37th percentiles will vote for A,
voters from the 38th to 62nd percentiles will vote for B, and 63rd to
100th will vote for C. The first round totals (as percentages) will be
37.5 - 25 - 37.5 and the centrist, B, will be eliminated first by a
margin of 12.5 percent.
If you assume a normal instead of uniform distribution of voters, with
candidates again at the top of the 25th, 50th, and 75th percentiles,
the results are nearly the same except the centrist is eliminated by a
margin of approximately 10.7 percent instead of 12.5.
It makes surprisingly little difference whether the voter distribution
curve is flat or bell-shaped. Even though the voters move inward with
a normal distribution, the location of the 25th and 75th percentiles
move inward as well (with a z-score of plus or minus 0.67 s.d.)
In either case, so long as the two wing candidates position themselves
anywhere between the 25th and 76th percentiles, there is no way for a
middle candidate to avoid being eliminated first. The best he can do
is try to mimic one of the wing candidates and hope for a
first-round tie.
Of course, as the wing candidates move toward the center, the centrist
loses by an even larger margin. Hence the term "center squeeze
effect".
Of course this changes if the candidates are skewed around more than
one policy dimension. Obviously where there is no centrist, there can
be no center-squeeze effect.
--
[email protected] people.clarityconnect.com/webpages3/davek
Dave Ketchum 108 Halstead Ave, Owego, NY 13827-1708 607-687-5026
Do to no one what you would not want done to you.
If you want peace, work for justice.
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