[EM] IRV inconsistency

Tue May 15 01:19:10 PDT 2001

Dear participants,

Forest Simmons wrote (14 May 2001):
> Here's an inconsistency of IRV that I wish somebody had told me about
> before I submitted my article to the Green Voice: It is possible for
> a candidate to "win" every precinct without winning the election.

Richard Moore wrote (14 May 2001):
> I had thought of this problem once before when thinking about IRV's
> failure to meet the Summability Criterion, but it wasn't on my mind when
> I reviewed your article. Every elimination in IRV means going back to the
> original ballots and eliminating the loser of the round, then recounting
> (you can sum the ballots into bins for each possible combination of votes
> such as A, AB, ABC, ACB, AC, ACD, etc., but this array gets very large
> very quickly as the number of candidates goes up, as we saw here a few
> weeks ago). That means per-precinct vote totals are useless. You have
> to do the elimination globally, not locally, and that means you can't
> predict the results from local data. Even if all localities pick the
> same winner.

Bart Ingles wrote (14 May 2001):
> The property not being met here is actually called "consistency", if
> I'm not mistaken.  Approval, Plurality, and Borda are consistent, but
> not many others.  Maybe some variants of those three.

Actually, the consistency criterion and the Condorcet criterion are
incompatible.

******

Richard Moore wrote (14 May 2001):
> Another consequence of the summability failure is that reporting IRV
> results will be very complicated. At least for Condorcet you could
> publish the overall pairwise matrix (and also the pairwise matrices for
> individual counties or precincts or whatever the desired resolution is).

I guess that IRV supporters will say that --for a voter to see what his
vote did-- it is sufficient to publish the votes of each IRV step.

Markus Schulze

FFrom election-methods-list-request at eskimo.com  Tue May 15 16:48:56 2001
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Subject: [EM] Florida 2001 Election Reform Law
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>> From: DEMOREP1 at aol.com
>> Subject: [EM] Florida 2001 Election Reform Law

Although it doesn't say so in the article you passed along,
as I recall the bill also prohibits lever machines.  And yet
those have been shown to be more reliable than the optiscan
machines.  The Florida law is the typical traffic light
installed only after someone gets run over.  Intersections
known to be just as dangerous get nothing.  It's not
encouraging.

>> The law can be seen at

>> http://www.leg.state.fl.us/Welcome/index.cfm

>> Type in S1118 in the upper left box and download the
>> enrolled bill pdf (103 pages).

>> One of the fraudulent *reforms* is abolishing the top 2
>> runoff primary in Florida *only* in 2002 (i.e. to make it
>> easier for incumbent legislators to win the 2002 plurality
>> winner primary elections).

>> Thus, as far as I know---

>> 41 States will have plurality primary winners

>> 9 States will have top 2 runoff primaries for the 2001-
>> 2002 new U.S. Representative and State legislature
>> gerrymanders due to the 2000 U.S.A. Census.

>> Plurality winners in general elections in all 50 States.

>> My standard general comment- any election reform method in
>> the U.S.A. has to be rather simple (due to simple-minded
>> politicians and judges and, of course, a fairly large
>> percentage of moron voters -- whatever method is being
>> used.).

>> Folks in many other countries with more accurate election
>> methods are political light-years ahead of the U.S.A.
>> -------

>> Jeb Bush signs Florida ban on punch card ballots

>> WEST PALM BEACH, Fla., May 9 (Reuters) - In the county at
>> the heart of last November's disputed presidential
>> election, Gov. Jeb Bush signed an election reform law on
>> Wednesday to end the era of punch cards, hanging chads and
>> butterfly ballots in Florida.
[...]

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From: Anthony Simmons <asimmons at krl.org>
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Subject: [EM] Yet another IRV problem
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From: Bart Ingles <bartman at netgate.net>
Subject: Re: [EM] Yet another IRV problem

>> Anthony Simmons wrote:
>> >
>> > >> From: Forest Simmons <fsimmons at pcc.edu>
>> >
>> > >> Why is IRV considered better than plurality when it fails
>> > >> this consistency test and also fails monotonicity?
>> >
>> > >> Is it only that it allows more ballot expressivity and
>> > >> more or less eliminates spoilage by tiny parties?
>> >
>> > I think the main reason is that it prevents what happened in
>> > Florida last year.  This is what people see, so this is what
>> > they want a cure for.

>> What exactly does it prevent?  Do you mean the situation
>> where Nader "spoiled" a close election, which would
>> otherwise have gone more decisively to Gore?  Don't

It would have eliminated the spoiler effect caused by
candidates who get a few percent of the vote. Like Nader.
That's what everyone saw, so that's their idea of what reform
should deal with.  At least that certainly is the impression
I've gotten.

>> forget, it could easily have gone the other way, in a
>> different election (or the same election, in a different
>> state):

All kinds of things could have happened.  But what people
saw, and therefore what they're reacting to, is the spoiler
effect, specifically in which the spoiler gets a small
percentage.

>> 50%   Bush
>> 45%   Gore
>>  5%   Nader, Gore

>> In other words, a decisive plurality election could have
>> been turned into a tie runoff.

That I don't quite follow.  You couldn't mean that Bush and
Gore could have tied, could you?