[EM] "Runoff Without Elimination," Condorcet efficiency

[Forest Simmons]

I like the idea of helping voters (by some good rule automatically
applied) choose a good final approval cutoff.

The method described below is an example of this.

As long as the method allows equal rankings at the top and bottom the
voters can over-ride the good intentioned help in the cases where they are
sure of which candidates they want to approve and disapprove.


On Tue, 9 Sep 2003, [iso-8859-1] Kevin Venzke wrote:

> Back in 1998 or so there was a method known as "Runoff Without Elimination"
> or "RWE."  I think it may have been devised by Donald.
>
> I'm not sure if this is a faithful reproduction of the rules, but I have
> programmed this:
> 1. The voter ranks candidates.  (As in Bucklin, voters should decide where to
> stop ranking.)
> 2. Initially count first-place rankings only.
> 3. While no one has votes from a majority (of ALL voters), AND non-eliminated candidates exist:
>    "Eliminate" the non-eliminated candidate with the fewest votes.
>    ("Eliminate" has no implied meaning besides what I'll say here.)
>    Recount the votes such that every voter approves their highest ranked
> non-eliminated candidate, as well as every eliminated candidate preferred to
> that non-eliminated candidate.  However, no one approves last-ranked (truncated)
> candidates.
> 4. Elect the candidate with the most votes.
>
> This may not seem interesting, except that it is very similar to IRV (but surely
> better), and to "AER" (and doesn't require an approval cutoff).
>
> I did an interesting experiment, I think.  Assuming everyone knows the identity
> of the sincere CW before voting, and everyone ranks down to and including the CW,
> but no lower, then it seems (based on my simulations) that the CW is always
> elected.
>
> There's the possibility that some factions will truncate the CW to try to beat
> him (an experiment I've yet to try), but this finding still seems interesting.
>
>
> Kevin Venzke
> stepjak at yahoo.fr
>
>
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