[EM] Party lists and candidate multiwinner elections
kathy.dopp at gmail.com
Mon Oct 20 08:49:36 PDT 2014
On Mon, Oct 20, 2014 at 11:22 AM, Kristofer Munsterhjelm
<km_elmet at t-online.de> wrote:
> So with that in mind, let me alter the example.
> You have a set of ballots that rank (or rate, or approve, etc) n candidates.
> First, consider the candidates to be parties and run a party list election
> with, say, 500 seats. k parties will be elected. Then run a k-seat
> multiwinner election using the same ballots, but let the candidates be
> Would there then be any situation where the set of parties that got at least
> one seat in the assembly would ideally differ from the set of candidates
> that got elected in the k-seat multiwinner election? If so, when and why?
You have the same number of voters but in the second election you have
500 - k fewer seats, so I'd say that, if you are asking are the k
candidates from the same k political parties, I'd say "no" because
some of those k parties won many more seats in the 500 set assembly
because those k political parties may have widely divergent support,
say one of the k parties had 50% of the support and another of the k
parties had only 1/100th of the support (not enough to merit one of k
Increasing the size of any legislature always decreases the size of a
voter group who merits at least one seat proportionately in it, and
> The reason I use a very large number of seats is to keep what one might call
> "quantization effects" to complicate the picture. Such effects happen when
> there aren't enough seats to represent each faction fairly, and thus a
> method might need to elect a compromise candidate instead. So, again, a
> better formal question might be "let the number of seats tend to infinity
> and the number of parties to elect be fixed at k. Assuming the party list
> method stabilizes in the limit, is or should then the subset of parties
> elected in a party list method be the same as the corresponding candidates
> elected by a k-winner multiwinner election method with the same ballots?".
> But again, I admit that it might be hard to reason about. Hence my
> unrestricted party list formulation.
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