Let's found an organization to oppose IRV

MIKE OSSIPOFF nkklrp at hotmail.com
Wed Nov 15 20:44:20 PST 2000

Craig Layton said:

>Note that the strategy of major parties crowding the centre seems to be
>equally applicable to Condorcet, Borda & Approval, with Demorep's YES/NO
>system being slightly worse, and *IRV and plurality being slightly better*.

No doubt the less sincere candidates (which will always include
the Republocrats) will always crowd the center, no matter what the
method is.

But if you're saying that's less of a problem with IRV than with
Condorcet & Approval, it isn't clear why you believe that.

When Merrill did his SU simulation study, he found that the
tendency of candidates to crowd the center greatly worsens IRV's
already poor SU performance.

When candidates crowd the center, or when there are many candidates,
IRV does worse at picking sincere CWs in Merrill's simulations.

Maybe you meant that Condorcet is more likely to pick CWs even when
they have low SU. But, as I said before, the popularity of the
voter median position will mean that there will be some well-known
and liked candidates there too. And, even if the sincere CW were
someone with nonpositional disutility for everyone for some reason,
as in the examples that show him with low SU, there's still a good
case for letting him be elected by the majority who prefer him to
the alternative. These improbable examples pit SU against the
rights of individual voters. There's a case for saying it's ok for
that majority of voters to be able to get their way, without
drastic strategy.

By the way, I think you're being a bit of a purist, regarding SU.
Those SU in the simulations are a rough estimate of how methods will
do. No one claims that everyone's numerical ratings really all
mean the same thing on the same scale. But estimated typical SU
given by those simulations are meaningful and useful. They
count a candidates disutility to a voter by the candidate's distance
from the voter in issue-space. Yes it's all only a rough estimate.
Maybe the idea is that the individual differences that you're
concerned about will tend to average out. The distances are a good
estimate of how much a voter dislikes a candidate, when we don't
know the details of each person's individual ratings scale, or how
each voter weights each issue. For the purpose of the SU simulations.

Some prefer to simply add the distances in the issue-dimensions
(the "city block metric"), but more prefer the Pythagorean distance,
in which changing a candidate's difference from you on an issue
where you differ greatly counts for more than changing it on another
issue on which you differ little.

Mike Ossipoff

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