[EM] Portland specifics, and ovals for approval cutoff
Chris Benham
cbenhamau at yahoo.com.au
Thu Jul 18 15:32:21 PDT 2024
> PSC is proportionality for solid coalitions
> <https://en.wikipedia.org/wiki/Proportionality_for_solid_coalitions>.
That link is to a rubbish page.
There is a proper criterion called Droop Proportionality for Solid
coalitions. Douglas Woodall from 1994:
>
> The most important single property of STV is what I call the/Droop
> proportionality criterion/or/DPC/. Recall that if/v/votes are cast in
> an election to fill/s/seats, then the quantity/v//(/s/+ 1) is called
> the/Droop quota/.
>
> * *DPC.*If, for some whole numbers/k/and/m/satisfying 0 </k/<=/m/,
> more than/k/Droop quotas of voters put the same/m/candidates (not
> necessarily in the same order) as the top/m/candidates in their
> preference listings, then at least/k/of those/m/candidates should
> be elected. (In the event of a tie, this should be interpreted as
> saying that every outcome that is chosen with non-zero probability
> should include at least/k/of these/m/candidates.)
>
> In statements of properties, the word "should" indicates that the
> property says that something should happen, not necessarily that I
> personally agree. However, in this case I certainly do: DPC seems to
> me to be a/sine qua non/for a fair election rule. I suggest that any
> system that satisfies DPC deserves to be called
> a/quota-preferential/system and to be regarded as a system of
> proportional representation (within each constituency)-an
> STV-lookalike. Conversely, I assume that no member of the Electoral
> Reform Society will be satisfied with anything that does not satisfy DPC.
>
> The property to which DPC reduces in a single-seat election should
> hold (as a consequence of DPC) even in a multi-seat election, and it
> deserves a special name.
>
> * *Majority.*If more than half the voters put the same set of
> candidates (not necessarily in the same order) at the top of their
> preference listings, then at least one of those candidates should
> be elected.
>
http://www.mcdougall.org.uk/voting-matters/ISSUE3/P5.HTM
Later he was calling that single-winner version "Majority for Solid
Coalitions", presumably because others were using "Majority" to mean
Majority for a Single Candidate and it's useful to have something short
that means that.
On 19/07/2024 7:00 am, Closed Limelike Curves wrote:
> PSC is proportionality for solid coalitions
> <https://en.wikipedia.org/wiki/Proportionality_for_solid_coalitions>.
>
> On Tue, Jul 16, 2024 at 11:07 AM Richard, the VoteFair guy
> <electionmethods at votefair.org> wrote:
>
> On 7/15/2024 3:20 PM, Closed Limelike Curves wrote:
> > Richard, I'd suggest taking a look at the newest
> > version of Wikipedia's PSC article (and the
> > citations in there); ...
>
> I don't recognize the PSC acronym.
>
> And I can't find it in Wikipedia's PSC list:
>
> https://en.wikipedia.org/wiki/PSC
>
> Also, I suggest changing the email "subject" to the full name of
> whatever PSC is.
>
> Richard Fobes
>
>
> On 7/15/2024 3:20 PM, Closed Limelike Curves wrote:
> > Richard, I'd suggest taking a look at the newest version of
> Wikipedia's
> > PSC article (and the citations in there); nonpartisan PR algorithms
> > other than STV are a very new field of research, and we're just
> barely
> > starting to study what algorithms satisfy what proportionality
> axioms.
> >
> > STV does try to put together a coalition, but this involves a
> very basic
> > greedy search for cohesive/solid coalitions that support a
> single group
> > of candidates. e.g. say a Hispanic Republican's preferences are
> > something like "vote for a Hispanic Republican, then non-Hispanic
> > Republicans, then a Hispanic Democrat"; whereas others Hispanic
> > Republicans care more about ethnicity than about party. In this
> > situation, there's no solid coalition for Hispanics /or/
> Republicans, so
> > it's very prone to underrepresent one of these groups. IIRC the
> EVC's
> > proposal for a proportional STAR algorithm works on basically
> the same
> > principle, as does anything that assigns seats
> sequentially/greedily,
> > which is why I tend to dislike them; whereas PAV is
> optimization-based,
> > so it tends to find better apportionments across cross-cutting
> > coalitions. I think Schulze STV also satisfies similar
> properties (but
> > only locally, because global optimization across committees
> requires
> > voters to give candidates ratings).
> >
> > On Sun, Jul 14, 2024 at 10:22 AM Richard, the VoteFair guy
> > <electionmethods at votefair.org
> <mailto:electionmethods at votefair.org>> wrote:
> >
> > On 7/13/2024 5:39 PM, Closed Limelike Curves wrote:
> > > ... my guess is the effect of STV is probably going to
> be limited
> > > compared to other methods, because STV is only
> proportional for
> > solid
> > > coalitions, i.e. voting blocs moving in perfect lockstep
> with each
> > > other, and only if they exceed a full quota. ...
> >
> > When using STV, coalitions don't need to be "solid."
> >
> > STV calculations automatically identify de-facto
> "coalitions." Each
> > candidate can be thought of as a de-facto coalition.
> >
> > One way to think of this concept is that STV gives any
> coalition a
> > "second try" when filling the second seat, and a "third try"
> when
> > filling the third seat.
> >
> > In contrast, IRV provides only "one try" for a coalition to
> elect their
> > candidate. So for IRV, a "solid" coalition voting with the
> same tactic
> > does have an advantage compared to a loose (non-solid)
> coalition.
> >
> > I'm not saying STV is better than PAV. I'm saying this specific
> > criticism of STV -- thinking that a coalition must be
> "solid" -- is not
> > a valid reason to dismiss STV.
> >
> > Richard Fobes
> >
> >
> >
> > On 7/13/2024 5:39 PM, Closed Limelike Curves wrote:
> > > Ahh, yeah, any PR method will outperform winner-take-all
> on this
> > metric.
> > > If cities are using STV for their city councils, that
> might imply
> > > single-winner IRV actively reduces minority representation.
> > >
> > > That said, my guess is the effect of STV is probably
> going to be
> > limited
> > > compared to other methods, because STV is only
> proportional for
> > solid
> > > coalitions, i.e. voting blocs moving in perfect lockstep
> with each
> > > other, and only if they exceed a full quota. So, for
> example, if
> > ethnic
> > > minorities tend to vote for a mix of white and minority
> > candidates, or
> > > if they're split across party lines (e.g. Hispanics only
> go about
> > 60-40
> > > for Democrats), this will tend to break up and dilute their
> > interests.
> > > It's not enough to have a quota of Hispanics who rate
> Hispanic
> > > Republicans and Hispanic Democrats highly; you need to have a
> > full quota
> > > rank /either/ a Hispanic Republican or a Hispanic
> Democrat at the
> > top of
> > > their ballots. The effect is the same as center-squeeze,
> where
> > your vote
> > > gets "stuck" with a weak candidate who nevertheless has
> enough first
> > > preferences to stay in the race for several rounds. By
> the time this
> > > candidate is eliminated, the more-electable candidates
> with fewer
> > first
> > > preferences have been defeated.
> > >
> > > But from what I can tell, this is much trickier to
> resolve than
> > > center-squeeze; proportional Condorcet methods don't seem
> to have
> > any
> > > guarantees on how out-of-whack a coalition can get,
> although I think
> > > Schulze STV has a nice local stability property.
> > >
> > > Most ethnic minorities aren’t solid coalitions, although
> > > African-Americans happen to be so overwhelmingly
> Democratic they
> > might
> > > act like one. Something like PAV that approximately
> satisfies the
> > core
> > > property should do better at giving minority voters more
> > representation.
> > >
> > > On Thu, Jul 11, 2024 at 8:40 PM Richard, the VoteFair guy
> > > <electionmethods at votefair.org
> > <mailto:electionmethods at votefair.org>
> > <mailto:electionmethods at votefair.org
> > <mailto:electionmethods at votefair.org>>> wrote:
> > >
> > > On 7/11/2024 10:47 AM, Closed Limelike Curves wrote:
> > > > ... given there's no theoretical basis to think
> IRV would
> > affect
> > > > city council and mayoral seats differently. ...
> > >
> > > In the new Portland elections, "ranked choice voting" for
> > city-council
> > > seats is STV (the Single Transferable Vote) with
> three seats per
> > > district, whereas "ranked choice voting" for Portland
> mayor is
> > > single-winner IRV (instant-runoff voting).
> > >
> > > Of course Portland's three-seats-per-district STV
> city-council
> > > elections
> > > are going to yield more gender and racial diversity
> compared to
> > > single-winner IRV for electing Portland's mayor.
> > >
> > > Richard Fobes
> > >
> > >
> > > On 7/11/2024 10:47 AM, Closed Limelike Curves wrote:
> > > > I'm going to go ahead and say I'm skeptical either
> of these
> > > results will
> > > > replicate, given there's no theoretical basis to
> think IRV
> > > would affect
> > > > city council and mayoral seats differently. My
> guess is
> > both results
> > > > would disappear if you used a hierarchical/partial
> pooling
> > model to
> > > > reduce the noise in the estimates.
> > > >
> > > > On Thu, Jul 11, 2024 at 10:45 AM Michael Garman
> > > > <michael.garman at rankthevote.us
> > <mailto:michael.garman at rankthevote.us>
> > > <mailto:michael.garman at rankthevote.us
> > <mailto:michael.garman at rankthevote.us>>
> > > <mailto:michael.garman at rankthevote.us
> > <mailto:michael.garman at rankthevote.us>
> > > <mailto:michael.garman at rankthevote.us
> > <mailto:michael.garman at rankthevote.us>>>>
> > > > wrote:
> > > >
> > > > And that’s bad! But it doesn’t negate the
> point I made. In
> > > council
> > > > races it helps. And that’s good!
> > > > On Thu, Jul 11, 2024 at 1:44 PM Closed
> Limelike Curves
> > > > <closed.limelike.curves at gmail.com
> > <mailto:closed.limelike.curves at gmail.com>
> > > <mailto:closed.limelike.curves at gmail.com
> > <mailto:closed.limelike.curves at gmail.com>>
> > > > <mailto:closed.limelike.curves at gmail.com
> > <mailto:closed.limelike.curves at gmail.com>
> > > <mailto:closed.limelike.curves at gmail.com
> > <mailto:closed.limelike.curves at gmail.com>>>> wrote:
> > > >
> > > > > In mayoral elections, RCV seems to
> *decrease*
> > gender and
> > > > racial/ethnic diversity.
> > > > Sounds substantial!
> > > >
> > > > On Thu, Jul 11, 2024 at 10:28 AM Michael
> Garman
> > > > <michael.garman at rankthevote.us
> > <mailto:michael.garman at rankthevote.us>
> > > <mailto:michael.garman at rankthevote.us
> > <mailto:michael.garman at rankthevote.us>>
> > > > <mailto:michael.garman at rankthevote.us
> > <mailto:michael.garman at rankthevote.us>
> > > <mailto:michael.garman at rankthevote.us
> > <mailto:michael.garman at rankthevote.us>>>> wrote:
> > > >
> > > > > In city council elections, RCV has
> a small but
> > > positive
> > > > effect on racial/ethnic diversity
> > > > Sounds substantial!
> > > >
> > > > On Thu, Jul 11, 2024 at 1:26 PM Closed
> > Limelike Curves
> > > > <closed.limelike.curves at gmail.com
> > <mailto:closed.limelike.curves at gmail.com>
> > > <mailto:closed.limelike.curves at gmail.com
> > <mailto:closed.limelike.curves at gmail.com>>
> > > > <mailto:closed.limelike.curves at gmail.com
> > <mailto:closed.limelike.curves at gmail.com>
> > > <mailto:closed.limelike.curves at gmail.com
> > <mailto:closed.limelike.curves at gmail.com>>>> wrote:
> > > >
> > > > Empirically, IRV adoption has no
> substantial
> > > effects on
> > > > diversity
> > > >
> > >
> >
> <https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/
> <https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/>
> <https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/
> <https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/>>>.
> In theory, I'd expect a small decrease in representation for
> minorities, because people of color tend to have higher rates of
> spoiled ballots, so IRV should hit them the hardest.
> > > >
> > > > In general, the theoretical
> advantages of IRV
> > > over FPP
> > > > are outweighed by its practical
> costs (spoiled
> > > ballots,
> > > > lower trust in elections, cost, etc.).
> > > > ----
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