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

[Kristofer Munsterhjelm]

On 02/24/2017 05:45 AM, robert bristow-johnson wrote:
>
> ---------------------------- Original Message ----------------------------
> Subject: Re: [EM] Proportional multi-winner ranked voting methods -
> guidelines?
> From: "Toby Pereira" <tdp201b at yahoo.co.uk>
> Date: Thu, February 23, 2017 5:09 pm
> To: "rbj at audioimagination.com" <rbj at audioimagination.com>
> "election-methods at lists.electorama.com"
> <election-methods at lists.electorama.com>
> --------------------------------------------------------------------------
>
>> I suppose it depends what you want from a multi-winner election. A
> faction of 51% could command all the seats if you did it that way.
>
>
> yes, i know that.  but, OTHER THAN GEOGRAPHIC division of the
> constituency into  groups (we might call those divisions "districts" or
> "wards"), i can't see how a government can legitimately divide the
> constituency into groups based on race or ethnicity or gender-preference
> identity, just to get proportional representation.  we can't have folks
> in Greenwich Village registering as gay or straight so that the gays get
> their allotted proportion and the straights getting their proportion.
>
> the alternative is that we elect someone to office even though *more* of
> us voters explicitly mark our ballots that we prefer someone else.
>  that's the whole point behind Condorcet compliance.
>
>
> ---------------------------- Original Message ----------------------------
> Subject: Re: [EM] Proportional multi-winner ranked voting methods -
> guidelines?
> From: "Kristofer Munsterhjelm" <km_elmet at t-online.de>
> Date: Thu, February 23, 2017 5:20 pm
> To: rbj at audioimagination.com
> "election-methods at lists.electorama.com"
> <election-methods at lists.electorama.com>
> --------------------------------------------------------------------------

>> A more proportional Condorcet method could be accomplished this way -- I
>> think that would be the most simple somewhat proportional Condorcet
>> method. For n seats:
>>
>> * Repeat lots of times:
>> - Randomly divide the voters into n groups
>> - Order the groups in random order.
>> - Determine the first group's winner according to the Condorcet method.
>> - Give the first seat to this winner and eliminate him from every
>> ballot (of every group).
>> - Determine the second group's winner, elect, and eliminate.
>> - Do so until you have n candidate assignments.
>> * Choose the assembly that you saw most often.
>>
>> In the 51/49 example above, it's basically a coin toss as to whether any
>> given group will elect one of {A,B,C,D} or one of {E,F,G,H}, and so you
>> get a 50-50 split.
>
> this is cool.  but the problem is in the lack of determinism (this
> "randomly" do anything will cause objection with some).
>
> is there a totally deterministic way to come up with these ensemble
> averages to get a good estimate of the proportional representation?
>  like the outcome should be that A, B, E, and F are winners if there are
> four seats in this multi-winner election. (and the simpler, the better.
>  the only way i can think of is to geographically subdivide the district
> into smaller and smaller into atomic communities or "microcosms".)

You could in theory integrate out the randomness, basically just 
mathematically find out what would happen if you could do it an infinite 
number of times. But that tends to make the algorithm a lot hairier, and 
then we might just be back to "what does this even do" levels of 
complexity for most voters.

Random methods can be very simple. Sortition is really powerful for its 
simplicity, for instance. So I guess the question would be, what would 
hinder the adoption of a proportional Condorcet method the most: 
complexity, or randomness?