[Slightly OT] Re: Voting

Eric egusenet at verizon.net
Thu Mar 25 18:06:06 CET 2004


Joe Mason <joe at notcharles.ca> wrote:

> In article <89feb3ba.0403241233.32ea8604 at posting.google.com>, Eric wrote:
> > Joe Mason <joe at notcharles.ca> wrote in message
> >news:<slrnc63985.3n2.joe at gate.notcharles.ca>...
> >
> >> (The crux of the flamewar is that Condorcet tends to elect
> >> "compromise candidates" who are few peoples' favourite but palatable to
> >> most, while IRV is more likely to elect people that are the first choice
> >> of a large block but hated by others.  Which is preferable is a matter
> >> of philosophy.)
> 
> <snip>
> 
> > I cannot see how IRV and a Condorcet method would differ should a
> > certain candidate receive a large block of first place votes. For if a
> > certain Candidate is the first choice of a large block, it has a
> > distinct advantage in both IRV and Condorcet over all the other
> > candidates, but will not necessarily be the winner in either.
> 
> I think the contentious scenario was two large opposed blocks and a
> small centrist block (C):
> 
> [redid the ballots to put them in a form accepted by online calculators]
>
> 49:A>C>B
> 48:B>C>A
> 3:C
>
> In Condorcet, we get:
> [snip]
> So C is the winner.  But, say the IRV proponents, only 3% of the
> population actually want C to win!

Yes, I understand this is the claim that some IRV proponents would make.
However, no such definitive statement can honestly be asserted based on
those ballots. With most (if not all) ranked ballot methods (including
Condorcet and IRV), if a voter truly does not want a Candidate to win,
the way the indicate that is by leaving that Candidate unranked.

In this case, the A & B voters did not leave C unranked. Both groups
clearly stated that they preferred C to their primary opponent.

What we do not know, because neither IRV nor Condorcet collects the
strength of the preference (there are inherent problems with doing such
a thing which is beyond the scope of this message), is how strong the
preference is for the A & B voters for C rather then their primary
opponent.

For example, it could be that:
(The numbers in parenthesis indicate the strength of how much the
candidates are liked on a linear 0 - 100 scale)

49 A(100) > C(99) > B(0)
48 B(100) > C(99) > A(0)
3: C(100)

Should this be true, one would be hard pressed to develop a credible and
compelling argument that C should not be the winner.

However, it is also possible that:

49 A(100) > C(1) > B(0)
48 B(100) > C(1) > A(0)
3: C(100)

In which case, an argument can be made that C should not be the winner.

But, like I stated, neither IRV nor Condorcet collect such information,
so, what is the fairest way to deal with this?

Both IRV and Condorcet both assume that your top choice has a strength
of 100. However, they differ greatly in the assumptions made about lower
preferences.

With IRV, if your top choice is eliminated, your second choice is
automatically promoted to a strength of 100, regardless of how you
actually feel about that candidate. For example, say a voter had voted
(I've included theoretical preference strengths):
  
  A(100) > B(1) > C(0)

but that A was eliminated. IRV recasts their vote as:

  B(100) > C(0)

A Condorcet method assumes that the strengths of the preferences should
be distributed evenly among the ranked candidates. I find this
assumption to be far more compelling in the general case because it is
simply not believable that all the A & B voters in any genuine situation
would have the exact same feelings towards the other candidates.
Condorcet makes assumptions about the average feeling towards the other
candidates.

It is also interesting to note that nearly every other ranked ballot
method will also select C as the winner. IRV seems to stand alone in the
assertion that the winner should be someone other then C.

Based on:
http://cec.wustl.edu/~rhl1/rbvote/calc.html
http://condorcet.ericgorr.net/
http://www.duniho.com/remote-mamcalc.php

> Anyway, the real question in this forum is whether Condorcet is a good
> method for voting on a PEP.  

If you would like to see how Condorcet and IRV behave with in genuine
ranked ballot elections, you can check out:

  http://ericgorr.net/library/tiki-index.php?page=BallotArchives

If anyone is aware of other places where ranked ballots from real
elections can be collected, let me know. I am working on collecting the
ranked ballots for the uk.* USENET hierarchy votes.







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