[EM] Proportional multi-winner ranked voting methods - guidelines?
robert bristow-johnson
rbj at audioimagination.com
Thu Feb 23 12:59:11 PST 2017
i wasn't aware that any STV would be Condorcet compliant (except for bottom-two runoff STV).
my only thought about a multi-winner method that *is* Condorcet compliant is to simply run the rank-choice election according to some Condorcet method (say Schulze or RP or MinMax or
BTR-STV), pick the Condorcet winner and assign that candidate to the first available seat, decrement the number of available seats by one, remove this winner from the candidate pool, and then see who the next Condorcet winner is from the remaining candidates. rinse and repeat until all
available seats are assigned.
what would be wrong with that approach to multi-winner elections?
--
r b-j rbj at audioimagination.com
"Imagination is more important than knowledge."
---------------------------- 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 2:08 pm
To: "VoteFair" <electionmethods at votefair.org>
"election-methods at lists.electorama.com" <election-methods at lists.electorama.com>
--------------------------------------------------------------------------
> Does the VoteFair method obey a specific proportionality property? For example, if you insist on electing the Condorcet winner, this is incompatible with Droop proportionality - e.g. https://groups.google.com/forum/#!topic/electionscience/n__VhVgjJqg
>
>
From: VoteFair <electionmethods at votefair.org>
> To: "election-methods at lists.electorama.com" <election-methods at lists.electorama.com>
> Sent: Thursday, 23 February 2017, 17:54
> Subject: Re: [EM] Proportional multi-winner ranked voting methods - guidelines?
>
> On 2/22/2017 3:45 PM, Richard Lung wrote:
> >
> > Don't understand your remark about STV ...
> > ... for a single national constituency.
> > ...
> > The HG Wells formula is "Proportional representation by the single
> > transferable vote in large constituencies."
>
> I assume you are referring to this statement:
>
> >> STV (the Single Transferable Vote) and similar methods(!) are designed
> >> for a small number of available seats, and it is a mistake to think
> >> that such a method can simply be used repeatedly to achieve fair
> >> results for a large number of available parliament seats.
>
> Although the designers think that they designed STV to handle a full
> national legislature/parliament, the method has the same flaw as
> instant-runoff voting (IRV), namely the method looks at each voter's
> currently top choice (after any candidate eliminations), and that
> approach -- of assuming the candidate with the most such "votes" is the
> most popular (or the inverse, assuming that the candidate with the
> fewest such votes is least popular) -- is extremely flawed.
>
> In other words, STV is like using single-mark ballots, except that when
> a voter's marked candidate is eliminated, then the voter automatically
> supplies an alternate single-mark ballot.
>
> In spite of that major unfairness/flaw, STV would provide reasonably
> acceptable results if only two seats were being filled. And if a nation
> has 3 equally dominant political parties, then filling 3 seats for each
> district would work.
>
> However, as I stated before, STV would not provide fair results if it
> were used for a full national legislature.
>
> Recently, in Canada, some people have been promoting the idea of using
> STV to elect about 5 MPs (members of parliament) from each district
> (which they call a "riding"). That would produce very unfair results!
> That's what I had in mind when I referred to using STV repeatedly.
>
> Although Schulze-STV uses pairwise counting, it still has the same flaw
> that it would not provide overall proportional results if it were used
> repeatedly to fill more than 2 (or maybe 3) seats in each district. And
> this method, and similar methods, would also provide flawed results if
> it were used to fill all the seats in a national legislature (and those
> reasons are explained in my book).
>
> So, OK, I was not clear about the meaning of the word "designed." I was
> referring to the effect of the design rather than the intention of the
> design.
>
> Richard Fobes
>
>
> On 2/22/2017 3:45 PM, Richard Lung wrote:
>>
>> Don't understand your remark about STV, the name given by Thomas Hare,
>> who invented it for a single national constituency. (Tho Mill was
>> prepared to be flexible about this, when he moved "Mr Hare's system" of
>> Personal Representation in parliament.
>> The HG Wells formula is "Proportional representation by the single
>> transferable vote in large constituencies."
>>
>> Agree with you about preference voting essential for fairness. Do you
>> have any good source for your assertion that the lack of it in European
>> party-proportional methods makes them especially vulnerable to moneied
>> influence?
>> You could say the same, for instance about the nuclear lobby in Britain
>> (tho not Scotland).
>>
>> from Richard Lung.
>>
>>
>>
>> On 22/02/2017 00:24, VoteFair wrote:
>>> On 2/20/2017 11:57 PM, Armando wrote:
>>> > ...
>>> > I am looking for multi-winner election with fair proportional
>>> > representation.
>>> > ...
>>> > I would very appreciate if you can help me giving “guidelines”,
>>> > explaining pros and cons, advising further readings. ...
>>>
>>> I suggest that you look at VoteFair ranking, which is a method I
>>> developed years ago, over a span of about a decade.
>>>
>>> It is described in detail in my book "Ending The Hidden Unfairness In
>>> U.S. Elections," which is available through multiple e-book reading
>>> platforms. The book includes lots of illustrations to make the
>>> concepts easier for "average" (non-math) readers to understand. (With
>>> so many illustrations the file size is large and the low price
>>> basically just covers the download fee.)
>>>
>>> Near the end of the book I explain that the same system would work in
>>> other nations simply by increasing the number of parliament members
>>> who are elected using cross-district voting methods.
>>>
>>> Based on your questions, here is what I think is the most important
>>> concept for you to understand:
>>>
>>> STV (the Single Transferable Vote) and similar methods(!) are designed
>>> for a small number of available seats, and it is a mistake to think
>>> that such a method can simply be used repeatedly to achieve fair
>>> results for a large number of available parliament seats.
>>>
>>> You seem to correctly understand that ranking candidates -- rather
>>> than using single-mark ballots -- is essential for fair results. PR
>>> (proportional representation) methods in Europe did not get this part
>>> of PR correct. That's why it is easy for campaign contributions
>>> (money) to easily control European politics.
>>>
>>> With these concepts in mind, I suggest that you read the overview of
>>> VoteFair ranking, which is here:
>>>
>>> http://www.votefair.org/calculation_details.html
>>>
>>> Or, for your convenience, here is a copy of those words, but without
>>> the links:
>>>
>>> ........ begin quote ..........
>>>
>>> VoteFair ranking is a calculation method that includes the following
>>> components:
>>>
>>> * VoteFair popularity ranking, which identifies the most popular
>>> choice, the second-most popular choice, the third-most popular choice,
>>> and so on down to the least popular choice. Here is a link to details
>>> about VoteFair popularity ranking.
>>>
>>> * VoteFair representation ranking, which identifies the
>>> most-representative choice (which is the same as the most popular
>>> choice according to VoteFair popularity ranking), the second-most
>>> representative choice, and additional representation levels. The
>>> second-most representative choice is identified after appropriately
>>> reducing the influence of the voters who are well represented by the
>>> most-popular (and most-representative) choice. Without this
>>> adjustment the same voters who are well-represented by the most
>>> popular choice could also determine the second-place winner. Here is
>>> a link to details about VoteFair representation ranking.
>>>
>>> * VoteFair party ranking, which identifies the most-popular political
>>> party (which is the same as the most popular choice according to
>>> VoteFair popularity ranking), the second-most popular political party
>>> (which is the same as the second-most representative choice), and the
>>> political party that deserves to be recognized as the third-most
>>> popular political party. The third-most popular party is identified
>>> after appropriately reducing the influence of the voters who are well
>>> represented by the first-ranked and second-ranked political parties.
>>> Without this adjustment the same voters who are well-represented by
>>> one of the most popular parties could create a "shadow" party that
>>> occupies the third position, which would block smaller parties from
>>> that third position. Here is a link to details about VoteFair party
>>> ranking.
>>>
>>> * VoteFair partial-proportional ranking, which identifies candidates
>>> who failed to win a legislative seat in their district, yet deserve to
>>> win special legislative seats for the purpose of compensating for
>>> unfair district boundaries, making it possible to elect legislators
>>> from "third" political parties (especially when the main political
>>> parties fail to fully represent their political priorities. Without
>>> this adjustment the balance of power among political parties in the
>>> legislature can easily fail to match the voters' preferences for
>>> political parties. Here is a link to details about VoteFair
>>> partial-proportional ranking.
>>>
>>> ........ end quote ..........
>>>
>>> For details about any part of VoteFair ranking, please go to the
>>> webpage and click the appropriate link.
>>>
>>> Thanks for your interest in learning how voting should be done!
>>>
>>> If you have questions, just ask.
>>>
>>> Richard Fobes
>>> Author of "The Creative Problem Solver's Toolbox" which has been
>>> published around the world in 10 languages
>>>
>>>
>>>
>>> On 2/20/2017 11:57 PM, Armando wrote:
>>>> Hello,
>>>> I am a new subscriber, and I am not an expert.
>>>>
>>>> I am looking for multi-winner election with fair proportional
>>>> representation.
>>>> I would like to find a method allowing voters to vote “transversally”
>>>> through parties: it could decrease conflicts.
>>>> I would very appreciate if you can help me giving “guidelines”,
>>>> explaining pros and cons, advising further readings. I thank you very
>>>> much in advance.
>>>>
>>>> I would like to open two issue:
>>>>
>>>> *1. Best multi-winner ranked method for a PROPORTIONAL ASSEMBLY*
>>>>
>>>> I read of CIVS
>>>> <http://civs.cs.cornell.edu/proportional.html> and Schulze-STV
>>>> <https://en.wikipedia.org/wiki/Schulze_STV>, and I thought they where
>>>> the best for my case.
>>>> They seems better then “traditional” STV since they satisfy more
>>>> criteria, with less strategic vote risk.
>>>> However I don’t understand differences among various condorcet’s
>>>> multi-winner systems.
>>>>
>>>> I knew also De Borda-based multiwinner systems:
>>>> _http://www.deborda.org/faq/_
>>>> It seems De Borda got popular in the spanish party of Podemos recently:
>>>> but they used a non-proportional De Borda to elect their national
>>>> assembly (with DesBorda
>>>> <https://vistalegre2.podemos.info/la-asamblea/#Sistema_de_votacion> by
>>>> Echenique).
>>>> Others in the same party proposed (failing) the Dowdall variant
>>>> <https://forms.podemos.info/wp-content/uploads/gravity_forms/247-6edda8669dd26a992ea894158e3e3d91/2016/12/PropuestaPodemosEnMovimiento.pdf>
>>>>
>>>> of De Borda (it is used in Nauru’s elections too). It seems it would
>>>> have been more proportional (here a simulation
>>>> <http://www.eldiario.es/politica/datos-cocina-votaciones-Podemos_0_612089572.html?utm_content=buffer93f9f&utm_medium=social&utm_source=facebook.com&utm_campaign=buffer>,
>>>>
>>>> 3rd figure, compare /Sistema utilizado (/DesBorda) with /Propuesta de
>>>> Anticapitalista/ (Dowdall-Borda)).
>>>>
>>>> However De Borda Institute recommends Quota Borda
>>>> System
>>>> http://www.deborda.org/faq/voting-systems/what-is-the-quota-borda-system-qbs.html
>>>>
>>>>
>>>> Actually I think there are few differences, for voters, between a
>>>> condorcet and a borda ballot (always numbering candidates). Is it?
>>>> But what are the difference in /results, /considering the proportional
>>>> variants?
>>>>
>>>> Do you think PR-open list system helps more the more “conflictual”
>>>> candidates (as could be the leader of each party, since they are
>>>> overexposed to party electors “love” and to opposers “hate”)?
>>>>
>>>> *2*. *Best multi-winner ranked method for a PROPORTIONAL MIXED-PARTIES
>>>> GOVERNMENT*
>>>> I was fascinated by De Borda Institute’s idea: a system to elect
>>>> directly a mixed government, where voters choose candidates AND best
>>>> offices for them.
>>>> They call it Matrix
>>>> Vote
>>>> http://www.deborda.org/faq/voting-systems/what-is-the-matrix-vote.html
>>>>
>>>> Could be possible to reach this purpose also with other systems, for
>>>> example Schulze-stv?
>>>>
>>>>
>>>> Best regards,
>>>> Thank you in advance
>>>>
>>>> Armando Pitocco
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>>
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>>
>>
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