[EM] Resume: Proportional multi-winner ranked voting methods - guidelines?

[Andrew Myers]

For what it's worth, the CIVS PR method satisfies Droop proportionality, 
and it's getting used in practice on a regular basis.

For example, in one recent election to choose the winner of a book 
award, the top 5 books were picked and they were #1, #2, #3, #4, and #17 
(!) in the nonproportional Schulze ordering. This seemed initially 
surprising but made sense because books #5-#16 all had at least one 
author in common with #1-#4.

-- Andrew

Toby Pereira wrote:
> By the way, a sensible Hare version of proportionality for solid 
> coalitions would be that for a faction to be guaranteed s seats, then 
> they should need s - 0.5 Hare quotas (or just over), rather than s 
> Hare quotas. In the single-winner case, this would translate to 50% of 
> the vote. This is what Sainte-Laguë guarantees.
>
>
> ------------------------------------------------------------------------
> *From:* Toby Pereira <tdp201b at yahoo.co.uk>
> *To:* Kristofer Munsterhjelm <km_elmet at t-online.de>; VoteFair 
> <electionmethods at votefair.org>; 
> "election-methods at lists.electorama.com" 
> <election-methods at lists.electorama.com>
> *Sent:* Monday, 5 June 2017, 18:09
> *Subject:* Re: [EM] Resume: Proportional multi-winner ranked voting 
> methods - guidelines?
>
> As I was saying before, while Droop proportionality has gained a lot 
> of currency as a criterion, it's just a special case of 
> proportionality for solid coalitions. We could just as easily talk 
> about Hare proportionality. For example, the Sainte-Laguë party list 
> method doesn't obey Droop proportionality, but is seen as more 
> mathematically proportional than D'Hondt, which does obey it. But 
> Sainte-Laguë does obey proportionality for solid coalitions more 
> generally. The point is that Droop proportionality itself is not a 
> deal breaker for a method, and I find it slightly overused.
>
> ------------------------------------------------------------------------
> *From:* Kristofer Munsterhjelm <km_elmet at t-online.de>
>
>
> Perhaps Droop proportionality isn't the exact proportionality measure
> one would want - for instance, for my Bucklin methods, I've tried to
> base them on divisor methods rather than on hard quotas - but I think
> the concept that "some voters who broadly agree on a group of candidates
> should see one of them elected" is a good one. That is, that a group of
> voters can have "their" seat without having to agree on a strategy.
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