[EM] Proportional election method needed for the Czech Green party - Council elections

[Peter Zbornik]

Dear Markus Schulze,

thanks for your reply.
Basically, I have to come up with some method or way to select one of the
two rankings you gave for A10, A12, A23, A33, A67.
That is a real problem.

Maybe we could use approval voting in this case to reduce the number of
candidates (hopefuls), I don't know.
These things happen in regression too when there are too many candidate
variables and too few data (forgot what it is called), therefore it is
standard to add a requirement that each variable (candidate) should be
significant in a univariate model at, say 5% or so in order to qualify as a
candidate in the multivariate model.
This requirement could for instance translate to a requirement of
eliminating the first X candidates, with the lowest Schulze-single winner
ranking (or the lowest share of preferences of the candidate on first M
places of the ballot) in the Schulze-STV election.
That heuristic could eliminate the candidates before they enter the model
and might resolve the ambiguities in some of the elections you describe.
R Fobes mentioned using approval voting to pre-select candidates.

I would like to send you an input file, but first I have to generate some
test-data.
I could start with some fictive elections, since we don't use ranked ballots
in our party.
A full-scale test will take some time to arrange.

By the way, out of pure curiosity, could a hybrid ranked ballot, i.e. a
ballot on the form A=B>C=D>E, be used in Schulze-STV in theory, without
sacrificing any of the good properties of the method?

Best regards
Peter Zborník

On Sun, May 9, 2010 at 5:26 PM, Markus Schulze <
markus.schulze at alumni.tu-berlin.de> wrote:

> Dear Peter Zbornik,
>
> you wrote (9 May 2010):
>
> > In your paper schulze3.pdf, there are some instances,
> > where the Schulze proportional ranking fails to produce
> > an unambiguous ordering (see for instance the result
> > for data set A10). Why do there ambiguities occur and
> > how would you recommend them to be resolved in a
> > deterministic manner without resorting to random number
> > generation etc?
>
> In 5 instances (A10, A12, A23, A33, A67), the Schulze
> proportional ranking is not unique. This is caused by
> the small numbers of voters and the large numbers of
> candidates.
>
> For example, in instance A10 (83 voters, 19 candidates),
> there are two possible Schulze proportional rankings:
> NAPMQFGRSLIBDJKEHOC and NMPQAFGRSLIBDJKEHOC.
>
> You wrote (9 May 2010):
>
> > Does Schulze-STV allow for truncated ballots? I.e. when
> > there are 5 candidates, does Schulze-STV allow me to
> > only rank two of them on my ballot?
>
> I recommend "proportional completion".
> This is explained in section 5.3 of
> http://m-schulze.webhop.net/schulze2.pdf
> and in the file calcul01.pdf of
> http://m-schulze.webhop.net/schulze3.zip
>
> You wrote (9 May 2010):
>
> > I am also curious to know, if you think it would be
> > difficult for you to implement a program, which would
> > handle the green council elections in an optimal
> > proportional manner, i.e. methods, which would only
> > impose the required ranking.
>
> It would be simple to incorporate all the requested
> specifications. Send me an input file with explanations.
>
> Markus Schulze
>
>
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