[Election-Methods] Matrix voting and cloneproof MMP questions

[Chris Benham]

Marcus,
Kristopher wrote:
"That MMP method would have to use some kind of reweighting
or those voters who got their way with regards to the  constituency 
members,..."

And you responded:
"Wow, that's exactly what I have proposed recently for
an STV-MMP system in Berlin."
I don't completely understand your papers, but your suggested
system seems to consider the individual voter's district vote and
party vote separately (i.e. each without regard to the other) so
I can't see how you "reweight voters" or have a completely fair
and satisfactory "top-up" system.

Wouldn't it still be the case that the district voter with no or only 
very weak preference between a candidate nominated by a party
that is sure to qualify and an independent does better to vote for 
the independent?

I would prefer some quasi-STV system that uses a jurisdiction-wide
uniform quota, something like this:
Voters (strictly?) rank from the top  candidates standing in their
district, and on the same paper also strictly rank from the top
lists of candidates for the jurisdiction-wide (quasi )top-up and
also may rank candidates within lists they rank. In both cases
truncation is allowed.
Select a uniform quota and use to elect candidates in the districts
STV-style.
Downweight each voters' top-up vote according to how much their
district votes contributed to winning candidates' quotas.
Use these reweighted votes to elect list candidates thus:
Eliminate all lists that don't qualify and IRV-style distribute preferences.
If the remaining list with the least votes doesn't have a quota, likewise
eliminate that list and so on until all remaining lists have at least one
quota. Each list then wins as many seats as it has quotas.

Then with the ballots that supplied each list's quota/s, use (regular) 
STV to determine which individual candidates fill the list's seats.

(By "qualify" I mean qualify according to the German constitution.)

A more sophisticated version might include some way of handling lists'
surplus votes.
Candidates should not be allowed to stand in more than one district,
but should be allowed to stand in both a district and on a  list.
Without being restricted by the German constitution the "top-up"
part could use the same method as the districts. If the jurisdiction as a 
whole could qualify as a "district" then perhaps this version wouldn't 
transgress the German constitution.

For  STV systems in general I don't see any great positive point in having
the numbers of seats for each district fixed before the votes are cast.
Why not wait until after and make the apportionment between districts
based on the numbers of votes cast?  That would tend to make the overall
result more proportional, and districts with higher turnouts would be rewarded\
with more seats.

Chris Benham


Marcus Schulze wrote (Sun Jul 6, 2008):

Dear Kristofer,

you wrote (6 July 2008):

> I've been reading about the "decoy list" problem in mixed
> member proportionality. The strategy exists because
> the method can't do anything when a party doesn't
> have any list votes to compensate for constituency
> disproportionality. Thus, "cloning" (or should it be
> called splitting?) a party into two parties, one for the
> constituency candidates, and one for the list, pays off.
> But is it possible to make a sort of MMP where that
> strategy doesn't work?
>
> That MMP method would have to use some kind of reweighting
> for those voters who got their way with regards to the
> constituency members, I think, because if the method
> just tries to find correlated parties, the party could
> theoretically execute the strategy by running all the
> constituency candidates as independents. What kind of
> reweighting would that be? One idea would be to have a
> rule that says "those with say x about the constituency
> vote gets 1-x in the list vote". Then vary x until the
> point of party proportionality is found. No matter what
> party someone who makes a difference with regards to the
> constituency candidate chooses, his vote loses power
> proportionally, and thus decoy lists wouldn't work.

Wow, that's exactly what I have proposed recently for
an STV-MMP system in Berlin. Please read these papers:

http://m-schulze.webhop.net/schulze4.pdf
http://m-schulze.webhop.net/schulze5.pdf

Read especially page 3 of paper "schulze5.pdf".

Markus Schulze



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