[EM] Condocet with many candidates - two round elections considered

[Peter Zbornik]

Hi Kevin,

thanks for your view on the topic.
In election-theoretic language, what criterion is used to describe, that a
method performs as well with many as with few candidates?
There is a list of criterias in the table at:
http://en.wikipedia.org/wiki/Schulze_method#Comparison_with_other_preferential_single-winner_election_methods,
but I don't know which it is (clone-independence? Maybe some other criterion
too?).

Peter


On 6/16/10, Kevin Venzke <stepjak at yahoo.fr> wrote:
>
> Hi Peter,
>
> --- En date de : Mer 16.6.10, Peter Zbornik <pzbornik at gmail.com> a écrit :
> >Dear all, dear Markus Schulze,
> >
> >after having presented Condorcet elections to some people in the Czech
> >green party, the following question came up.
> >Condorcet elections might work with three candidates, but what about if
> >there are twenty of them, will the system work and elect the best
> >candidate?
>
> In my opinion, in theory, Schulze performs exactly as well with many as
> with few candidates.
>
> >Q1: What would you answer for Condorcet elections in general and Schulze-
> >method elections in particular?
>
> I would not say Condorcet in general is excellent at this, but Condorcet
> fans tend to prefer methods that don't break when you have many candidates.
>
> >Q2: Specifically, would you recommend a two-round construct, i.e. the
> >three best candidates (or x best?) meet in the second round.
>
> The only reason I would recommend something like this is if you expect
> that voters may not be familiar with the strongest candidates. If voters
> do not obtain *new* knowledge between rounds, and their preferences don't
> change, then the pairwise contests among them are going to be exactly
> the same, and the Schulze result would most likely be the same.
>
> >Q3: Would such a two-round system help to deal with the case of the "dark
> >horse" winning with long beat-paths and people being dissatisfied with
> >the election?
>
> If the "dark horse" can win in this way (more likely: he wins because
> everyone gives him a mid-range preference and he defeats everyone) he will
> most likely still win when you eliminate all but a few candidates. So
> again, a second round only makes a difference if the voters are supposed
> to get new information and change their preferences.
>
> The ordinary two-round method is different from this because when you
> eliminate candidates, the "best" candidate could very easily change, since
> it's all based (in theory) on who is everyone's favorite candidate.
>
> Kevin Venzke
>
>
>
>
> ----
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