[EM] Instant 2-stage plurality/pairwise runoff

[Steve Barney]

I am interested in the fact that the traditional 2 stage plurality runoff will
always choose a Condorcet Candidate, when one exists, if that candidate is
among the top 2 plurality candidates in the first round. This suggests that we
should consider an instant 2-stage runoff procedure where preference ballots
are used, and the top two plurality candidates go into an instant pairwise
vote. Do you know if this sort of method has been written about or used?
Presumably, the advantage of the preference ballot is that the procedure would
then be less manipulable. I haven't thought this thru yet, but that is my
guess.

SB

--- In election-methods-list at y..., "MIKE OSSIPOFF" <nkklrp at h...> wrote:
[...]
> Steve continued:
> 
> That was
> illustrated by my highlighting of the fact that the plurality vote is the 
> only
> positional voting procedure which always elects a majority candidate when 
> one
> exists
> 
> I reply:
> 
> What do you mean by a majority candidate? If you mean a candidate
> who is favorite to a majority, then Plurality doesn't always elect
> a majority candidate when one exists. Not unless you stipulate sincere
> voting, which would be fantasy in Plurality.
> 
> If you mean a candidate whose vote total exceeds half the number
> of voters, Approval & CR always elect a majority candidate when
> they exist.
> 
> But we can say this for Plurality: It's the only method that always
> elects the candidate voted the most favorite. Yes, that's almost
> a repetition of Plurality's definition, but it's still true, and it
> still sounds more desirable than undesirable.
> 
> Obviously that criterion conflicts with most of those that are
> important to most of us, and so we politely pass up Plurality and
> choose methods that meet criteria more important to us.
> 
> Still, it's worth pointing out that IRV can fail to elect a sincere
> CW or a voted CW even if s/he is the voted favorite of more people
> than any other candidate, and that even Plurality won't do that.
> 
> In Runoff, a sincere CW can't lose if s/he comes in 1st or 2nd in
> the primary. That's a very big advantage for Runoff compared to IRV.


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