<div dir="ltr">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.<div><br></div><div>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 <i>or</i> 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).</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Jul 14, 2024 at 10:22 AM Richard, the VoteFair guy <<a href="mailto:electionmethods@votefair.org" target="_blank">electionmethods@votefair.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On 7/13/2024 5:39 PM, Closed Limelike Curves wrote:<br>
> ... my guess is the effect of STV is probably going to be limited<br>
> compared to other methods, because STV is only proportional for solid<br>
> coalitions, i.e. voting blocs moving in perfect lockstep with each<br>
> other, and only if they exceed a full quota. ...<br>
<br>
When using STV, coalitions don't need to be "solid."<br>
<br>
STV calculations automatically identify de-facto "coalitions." Each <br>
candidate can be thought of as a de-facto coalition.<br>
<br>
One way to think of this concept is that STV gives any coalition a <br>
"second try" when filling the second seat, and a "third try" when <br>
filling the third seat.<br>
<br>
In contrast, IRV provides only "one try" for a coalition to elect their <br>
candidate. So for IRV, a "solid" coalition voting with the same tactic <br>
does have an advantage compared to a loose (non-solid) coalition.<br>
<br>
I'm not saying STV is better than PAV. I'm saying this specific <br>
criticism of STV -- thinking that a coalition must be "solid" -- is not <br>
a valid reason to dismiss STV.<br>
<br>
Richard Fobes<br>
<br>
<br>
<br>
On 7/13/2024 5:39 PM, Closed Limelike Curves wrote:<br>
> Ahh, yeah, any PR method will outperform winner-take-all on this metric. <br>
> If cities are using STV for their city councils, that might imply <br>
> single-winner IRV actively reduces minority representation.<br>
> <br>
> That said, my guess is the effect of STV is probably going to be limited <br>
> compared to other methods, because STV is only proportional for solid <br>
> coalitions, i.e. voting blocs moving in perfect lockstep with each <br>
> other, and only if they exceed a full quota. So, for example, if ethnic <br>
> minorities tend to vote for a mix of white and minority candidates, or <br>
> if they're split across party lines (e.g. Hispanics only go about 60-40 <br>
> for Democrats), this will tend to break up and dilute their interests. <br>
> It's not enough to have a quota of Hispanics who rate Hispanic <br>
> Republicans and Hispanic Democrats highly; you need to have a full quota <br>
> rank /either/ a Hispanic Republican or a Hispanic Democrat at the top of <br>
> their ballots. The effect is the same as center-squeeze, where your vote <br>
> gets "stuck" with a weak candidate who nevertheless has enough first <br>
> preferences to stay in the race for several rounds. By the time this <br>
> candidate is eliminated, the more-electable candidates with fewer first <br>
> preferences have been defeated.<br>
> <br>
> But from what I can tell, this is much trickier to resolve than <br>
> center-squeeze; proportional Condorcet methods don't seem to have any <br>
> guarantees on how out-of-whack a coalition can get, although I think <br>
> Schulze STV has a nice local stability property.<br>
> <br>
> Most ethnic minorities aren’t solid coalitions, although <br>
> African-Americans happen to be so overwhelmingly Democratic they might <br>
> act like one. Something like PAV that approximately satisfies the core <br>
> property should do better at giving minority voters more representation.<br>
> <br>
> On Thu, Jul 11, 2024 at 8:40 PM Richard, the VoteFair guy <br>
> <<a href="mailto:electionmethods@votefair.org" target="_blank">electionmethods@votefair.org</a> <mailto:<a href="mailto:electionmethods@votefair.org" target="_blank">electionmethods@votefair.org</a>>> wrote:<br>
> <br>
> On 7/11/2024 10:47 AM, Closed Limelike Curves wrote:<br>
> > ... given there's no theoretical basis to think IRV would affect<br>
> > city council and mayoral seats differently. ...<br>
> <br>
> In the new Portland elections, "ranked choice voting" for city-council<br>
> seats is STV (the Single Transferable Vote) with three seats per<br>
> district, whereas "ranked choice voting" for Portland mayor is<br>
> single-winner IRV (instant-runoff voting).<br>
> <br>
> Of course Portland's three-seats-per-district STV city-council<br>
> elections<br>
> are going to yield more gender and racial diversity compared to<br>
> single-winner IRV for electing Portland's mayor.<br>
> <br>
> Richard Fobes<br>
> <br>
> <br>
> On 7/11/2024 10:47 AM, Closed Limelike Curves wrote:<br>
> > I'm going to go ahead and say I'm skeptical either of these<br>
> results will<br>
> > replicate, given there's no theoretical basis to think IRV<br>
> would affect<br>
> > city council and mayoral seats differently. My guess is both results<br>
> > would disappear if you used a hierarchical/partial pooling model to<br>
> > reduce the noise in the estimates.<br>
> ><br>
> > On Thu, Jul 11, 2024 at 10:45 AM Michael Garman<br>
> > <<a href="mailto:michael.garman@rankthevote.us" target="_blank">michael.garman@rankthevote.us</a><br>
> <mailto:<a href="mailto:michael.garman@rankthevote.us" target="_blank">michael.garman@rankthevote.us</a>><br>
> <mailto:<a href="mailto:michael.garman@rankthevote.us" target="_blank">michael.garman@rankthevote.us</a><br>
> <mailto:<a href="mailto:michael.garman@rankthevote.us" target="_blank">michael.garman@rankthevote.us</a>>>><br>
> > wrote:<br>
> ><br>
> > And that’s bad! But it doesn’t negate the point I made. In<br>
> council<br>
> > races it helps. And that’s good!<br>
> > On Thu, Jul 11, 2024 at 1:44 PM Closed Limelike Curves<br>
> > <<a href="mailto:closed.limelike.curves@gmail.com" target="_blank">closed.limelike.curves@gmail.com</a><br>
> <mailto:<a href="mailto:closed.limelike.curves@gmail.com" target="_blank">closed.limelike.curves@gmail.com</a>><br>
> > <mailto:<a href="mailto:closed.limelike.curves@gmail.com" target="_blank">closed.limelike.curves@gmail.com</a><br>
> <mailto:<a href="mailto:closed.limelike.curves@gmail.com" target="_blank">closed.limelike.curves@gmail.com</a>>>> wrote:<br>
> ><br>
> > > In mayoral elections, RCV seems to *decrease* gender and<br>
> > racial/ethnic diversity.<br>
> > Sounds substantial!<br>
> ><br>
> > On Thu, Jul 11, 2024 at 10:28 AM Michael Garman<br>
> > <<a href="mailto:michael.garman@rankthevote.us" target="_blank">michael.garman@rankthevote.us</a><br>
> <mailto:<a href="mailto:michael.garman@rankthevote.us" target="_blank">michael.garman@rankthevote.us</a>><br>
> > <mailto:<a href="mailto:michael.garman@rankthevote.us" target="_blank">michael.garman@rankthevote.us</a><br>
> <mailto:<a href="mailto:michael.garman@rankthevote.us" target="_blank">michael.garman@rankthevote.us</a>>>> wrote:<br>
> ><br>
> > > In city council elections, RCV has a small but<br>
> positive<br>
> > effect on racial/ethnic diversity<br>
> > Sounds substantial!<br>
> ><br>
> > On Thu, Jul 11, 2024 at 1:26 PM Closed Limelike Curves<br>
> > <<a href="mailto:closed.limelike.curves@gmail.com" target="_blank">closed.limelike.curves@gmail.com</a><br>
> <mailto:<a href="mailto:closed.limelike.curves@gmail.com" target="_blank">closed.limelike.curves@gmail.com</a>><br>
> > <mailto:<a href="mailto:closed.limelike.curves@gmail.com" target="_blank">closed.limelike.curves@gmail.com</a><br>
> <mailto:<a href="mailto:closed.limelike.curves@gmail.com" target="_blank">closed.limelike.curves@gmail.com</a>>>> wrote:<br>
> ><br>
> > Empirically, IRV adoption has no substantial<br>
> effects on<br>
> > diversity<br>
> > <br>
> <<a href="https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/" rel="noreferrer" target="_blank">https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/</a> <<a href="https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/" rel="noreferrer" target="_blank">https://www.newamerica.org/political-reform/reports/rcv-impact-on-candidate-entry-and-representation/</a>>>. 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.<br>
> ><br>
> > In general, the theoretical advantages of IRV<br>
> over FPP<br>
> > are outweighed by its practical costs (spoiled<br>
> ballots,<br>
> > lower trust in elections, cost, etc.).<br>
> > ----<br>
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> > for list info<br>
> ><br>
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</blockquote></div>