[EM] an extra step for IRV (and some other methods?)

[Michael Ossipoff]

The extra step described below sounds like the "Voter's Choice" that I used
in one or more EM polls.

The reason for Voter's Choice was: We wanted to choose a winner, when we
didn't agree on what voting system to use. Especially a problem when voting
to elect a winning voting system, but just as much a problem in any
election without a pre-chosen voting system.

I suggested the following:

1. Every main balloting system discussed here is included. Approval,
rank-balloting, and Ratings(0-100) were
included. A more up-to-date mix would include 3-slot balloting,as did the
poll that I proposed a few months ago.

2. As part of the ballot, the voter is invited (but not required) to
designate noiminated method.

3. All of the ballotings are used, to count all of the methods that have
been nominated.

4. If you have designated method M, then your ballot gives an Approval vote
to every candidate who is ranked, in your ranking,  at least as high as M's
winner.

In other words, you are using M, the method that you most trust to find the
CW, to choose how far down you should approve. If you know, or strongly
suspect, which candidate is the CW, then, in Approval, one good strategy is
to approve down to that CW. (I didn't mention that strategy, among the
Approval strategies that I described, because ordinarily a person doen't
have information about who the CW is--But the choice made by M might be
regarded as giving you a good guess about who the CW is.).

5. The winner is the candidate who gets the most approvals from paragraph
#4.

 (But, instead of designating a method, you could, alternatively, designate
"Manual". That means that you
want your Approval ballot (part of the overall poll balloting) to give your
approvals for the purposes of paragraph
#5's count--instead of giving those paragraph-#5-count approvals as
described in paragraph #4).

(The results of the poll's Approval balloting are counted too, and
reported. But the winner of the poll is the result
of the aggregation that I've described, completed byand which I called
"Voter's Choice".

I should add that, in the poll that I proposed a few months ago, I used a
slightly different version of Voter's Choice.

In that other version, which I'll now call Voter's Choice 2, likewise
counts every nominated method. It gives to each
method's winner, a number of points equal to the number of people who
designated that method. The winner is the candidate who receives the most
points.

That makes sense, because it amounts to weighting each method according to
the number of people designating that method.

But that can also be regarded as letting each voter give a Plurality vote
to the candidate chosen by his/her
designated method. So it occurred to me (or someone): Why not make it an
_Approval_ vote instead, wherin the voter approves down to the choice made
by his designated method.

I'm not sure, but that change might have been suggested by Forest.

But it hadn't occurred to me to use a procedure similar to Voter's Choice
when only one method is used. It would be
interesting to find out if it brings improvement in regards to the
properties that I consider important.

Mike Ossipoff








On Wed, May 2, 2012 at 1:09 AM, C.Benham <cbenhamau at yahoo.com.au> wrote:

> I have an idea for adding an extra step to IRV which has the effect of
> throwing out its compliance with Later-no-Harm in exchange for Minimal
> Defense, while trying to hang on to Later-no-Help.
>
> *Voters strictly rank from the top  however many or few candidates they
> wish. Until one candidate remains, provisionally eliminate the candidate
> that is highest ranked (among candidates not provisionally eliminated) on
> the fewest ballots. The single candidate left not provisionally eliminated
> is the provisional winner P.
>
> [So far this is IRV, used to find a "provisional" winner. Now comes the
> extra step.]
>
> Interpreting candidates ranked above P as approved and also P as approved
> if ranked, elect the most approved candidate.*
>
> This method might be called "IRV-pegged Approval" (IRVpA). It is more
> Condorcet-consistent than IRV, because when IRVpA produces a different
> winner that candidate must pairwise beat
> the IRV winner  (so it keeps IRV's compliance with Mutual Dominant Third).
>  Also the IRVpA winner must be more approved than the IRV winner.
>
> I'd be interested if anyone can show that this fails Later-no-Help.
>
> Some other methods might gain from adding the same extra step, for example
> Schulze(Margins), MinMax(Margins) and Descending Solid Coalitions.
> It will fix any failures of  Minimal Defense (and my  Strong Minimal
> Defense criterion) and Plurality.
>
> Chris Benham
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20120502/b47e7a2f/attachment-0004.htm>