[EM] Portland specifics, and ovals for approval cutoff
Closed Limelike Curves
closed.limelike.curves at gmail.com
Mon Jul 15 15:20:27 PDT 2024
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> 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>>
> 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>>>
> > > 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>>> 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>>> 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>>> 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/>>.
> 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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