[EM] Condorcet meeting

[Colin Champion]

Mostly I agree with Chris.

It's hard to say how many candidates should make it through to the final 
(Condorcet) round of voting. We can only guess at how effective the 
proposed primary methods would be, and our knowledge of the performance 
of ranked voting systems is based largely on idealised evaluations.

I posted some figures a while ago indicating that as the level of 
truncation increased, some strange reversals set in just after the 
half-way mark: the Borda count briefly gained in accuracy while 
Condorcet methods started a headlong fall. After this point the Borda 
count outperforms Condorcet methods. (The figures relate to sincere 
voting; there's no suggestion that Condorcet methods become more 
manipulable than the Borda count.) This suggests that we should keep the 
field small enough to expect voters to rank at least half the 
candidates, or motivate them to rank more than they would naturally be 
inclined to, or abandon standard voting theory in favour of methods 
tailored to truncated ballots. I have a suggestion on the second head 
which I'll make in another thread.

I think I favour a fixed maximum field size. We want to ensure that the 
number of candidates is not more than will be voted on accurately; we 
don't want to discard the candidate closest to the median of the voter 
distribution; jointly satisfying these two desiderata requires a fair 
degree of subtletly, and there are other parts of the election system 
which will give better rewards to algorithmic complexity.

CJC

On 30/08/2023 09:17, Chris Benham wrote:
>
>
> Kristofer,
>
> IMHO this is all far too complicated and completely wrong-headed.
>
> For one thing, it seems to assume that major candidates have some 
> interest in,
> or in some way benefit from, displacing minor candidates off the final 
> ballot.
>
> In fact, with voluntary voting, they are just as likely to be harmed 
> by them doing that
> as helped.  Major moderate wing candidates can benefit by minor (sure 
> loser) more extreme
> candidates on the same wing being on the ballot, because they inspire 
> more voters to turn out
> who will help that moderate wing candidate to defeat the other major 
> candidate/s.
>
> So with your suggested method, a candidate could lose the election 
> because it did too well in
> the primary.
>
> I only recently saw the first message in this thread, and was a bit 
> surprised that the N suggested
> was so small and elastic ("2-5").
>
> My suggested solution assumed a fixed N.  I would have no problem with 
> 7, certainly at least 5.
>
> If we are happy to have N elastic because we don't want any very weak 
> candidates on the ballot,
> then we can do IRV-style eliminations and vote transfers until the 
> lowest tally of any not eliminated
> candidate meets some arbitrary threshold and then we stop.
>
> Or we can combine that with saying we are going to have at most X 
> candidates.
>
> I think I prefer a quite high fixed number.  Lots of candidates can 
> help inspire turnout and make for
> a wider and more interesting "battle of ideas".
>
> Chris B.
>
>
>
>
>
>
>> *Kristofer Munsterhjelm* km_elmet at t-online.de 
>> <mailto:election-methods%40lists.electorama.com?Subject=Re%3A%20%5BEM%5D%20Condorcet%20meeting&In-Reply-To=%3Ca4347551-24f9-f38b-be5b-bb3da1a4f5e3%40t-online.de%3E>
>> /Mon Aug 28 12:37:50 PDT 2023/
>>
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>>
>>
>> ------------------------------------------------------------------------
>> On 8/28/23 19:24, Forest Simmons wrote:
>> >/For practical purposes, this appeals to me the most so far. />//>/But the question remains about how to determine the number N. />//>/Why not just use the number ranked (or approved, as the case may be) on />/the average primary ballot? /
>> Here's a similar approach with an idea to preserve a kind of clone
>> independence:
>>
>> Use STV, but don't eliminate candidates when they're elected, just
>> reweight the ballots according to surplus instead.
>>
>> When a candidate is elected again, he only appears once in the final
>> outcome, but the number of candidates in the outcome is reduced by one
>> instead. In effect, the duplicate election leads to the election of a
>> "hole" that takes up a spot without assigning any candidate to that spot.
>>
>> Say N = 5, so that the Droop quota is 1/6. Then a candidate with
>> above-majority support (say 1/2 + epsilon) gets three such quotas, and
>> is elected three times: once to get into the finalist set, and twice
>> more to reduce the number of other candidates from four to two.
>>
>> The idea is that if the candidate were to be cloned, then these clones
>> would occupy three spots of the outcome, so the result is the same; just
>> in one case, there's only one winner from that bloc and two "holes",
>> while in the other case, there would be three winners from the bloc.
>>
>> I would probably reserve one of the five spots for the primary CW,
>> though. Ideally it would use a proportional ordering or a pairwise STV
>> variant, but then we're moving into "deluxe, complex method" territory.
>

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