Posts made by Keith Edmonds

Does anybody want to go here today to tell them that partisan voting and ranking is not going to lower polarization?

https://us02web.zoom.us/webinar/register/WN_1CuGeJwbQN2ozR3EnzM2eg

@andy-dienes Awesome. Pandas definitely can make things concise if done right. There are lots of functions.

@andy-dienes said in Threshold MES:

Added a Julia implementation to the electowiki page. If people want it in Python I can translate.

My preference is python with heavy use of the pandas library. This should help it be short an clean. Or at leas shorter than what you have there. We do not really want production code but a very precise definition.

@andy-dienes OK that is what I would have expected. I think this is now my second favourite system (second to SSS but we do not need to side-track). It meets the basic criteria I look for

• It is simple enough to be explained in a referendum to laypeople
• It has an underlying ethos which makes sense. It is not the linear utilities like SSS but it is reasonable and consistent.
• It gives a high level of proportionality
• It gives good voter expression (ie cardinal ballots)

Unless there is a large flaw I am missing (like nonmonotonicity) I think you should run it past experts who are not on here (ie Piotr and Jameson) to see if they have comments.

It is quite similar to Sequential Monroe Voting so I would take a good look at that. The two finalists in the last Committee on voting methods was this and SSS. Allocated score was sort of reinvented as a compromise between the two.

Possible names for this system

• Threshold Allocation Voting
• Proportional Threshold Selection
• Something else with the words Proportional, Threshold, Allocation, Justified.

OK good. It does not seem to have that issue. Thanks for humouring me, I could not quite remember the reason for not wanting to order by original score

@andy-dienes said in Threshold MES:

BBBAB

I would think this is the better result but whatever. To explore this I find the following example which I often refer to illustrative.

@keith-edmonds said in Rule X extended to score ballots:

Consider this 5 winner example with clones for each candidate
Red: 61% vote A:5, B:3, C:0
Blue: 39% vote A:0, B:3, C:5

RRV Gives ['A1', 'C1', 'A2', 'B1', 'B2']
MES Gives ['A1', 'A2', 'A3', 'C1', 'B1']
SSS Gives ['A1', 'B1', 'B2', 'B3', 'B4']
Allocated score Gives ['A1', 'B1', 'A2', 'B2', 'A3']
STV Gives ['A1', 'A2', 'A3', 'C1', 'C2']

What does your new system give?

@andy-dienes I understand that it is an allocation method so it is all or nothing unless on the split point. I also understand that you want to charge them all the same cost when it is on a split point.

I was thinking that a voter with a ballot weight 0.4 will contribute that 0.4 weight to all candidates they score a 5, BUT the 5 would be sequenced as 2. This means a person who scored the same candidate 3 would be taken first. There is a strategic issue around this but I don't recall the details. We encountered it when designing Allocated score. I suggest you look into the issue. It is linked on electowiki here but the link is broken since the CES forum has been taken down.

@andy-dienes said in Threshold MES:

The disadvantage would be that it respects linear / additive utility much less; for example it will not necessarily choose the score winner (although in practice probably will) and the distribution of utility (again, assuming it is linearly additive over sets) is not as proportional as in regular MES.

Does the system lower the threshold in integer increments? In later rounds the score could be a fraction.

I do like this system a lot and it is simple enough to be viable. It reminds me a bit of Sequential Monroe. I do not think Threshold MES is really the best name.

@andy-dienes I like this system. Is there a clear disadvantage to regular MES? There is a pretty clear simplicity advantage.

Please correct me if either of the following is wrong

• The subtracted voting power is done as "scaling" to the rest of the ballot
• The threshold will always decrease as sub sequent winners are elected.

@toby-pereira OK, makes sense. The one round run off version of that is STAR and the every round run off is Cardinal Baldwin. Presumably you prefer this because it maximizes voter influence. I invented STLR specifically to avoid that as it leads to majoritarianism.

It seems there are (at least) three types. This one. The one STLR uses. And the one for IRNR and Distributed Voting

I propose that these should all be consider them all the same class for this poll. Do you agree? Wanna suggest a name? I gave one above.

@toby-pereira On the contrary. I agree with all your points and you will get no wrath. I have purposely not attempted to gain traction for STLR since STAR is the better choice for lobbying.

I think it would be best to have a class containing IRNR, Cardinal Baldwin, STLR and other reweighting methods. Brian Olson, Aldo Tragni, myself and some others have put a lot of time into the development of this class. STAR is technically in this class but it is on the edge of it. For that and reasons I mentioned before STAR should stand alone.

While we are on the topic, if you consider the reweighting method of STLR to be misguided then by extension you would also consider cardinal Baldwin to be misguided. Is there a reweighting system which you think if better?

@rob I would put them in the same class as STLR and STAR.... I think. They are all directed towards trying to reweight the scores as you eliminate losers.

STAR and STLR do it for the final round while several others do it at each round. The cost of doing it a each round is that you lose monotonicity and there is a fair bit of added complexity. In my mind they all have the same intent so it would be fair to put them together. "reweighted cardinal run-off methods" or something like that would be a reasonable name.

All that said, It would be a shame to lump all such systems of varying quality together with a frontrunner like STAR. Could I propose that commonly used systems like Approval, STAR and IRV stand alone while other systems with no lobby behind them get grouped?

@rob Thank you for including STLR. I do still advocate for this system. I think it is better than STAR but I do not think it is viable in the current climate of voting reform for a number of reasons. I favour STAR publicly.

Which class are sequential elimination reweighted systems like Cardinal Baldwin and IRNR? STAR and STLR may be better to be paired as a single auto run-off class.

rc-i[0] rc-c[2] c-c[6] star[9] appr[7] score[9] stlr[10] c-med[3] c-o[1]

@andy-dienes First, lets never associate this with Later-no-harm as I hate that property like none other.

Anyway, I have thought about this for a few days and I do not think it is possible. Just because adding constraints on the process is a non-standard concept in voting theory does not mean it should not be. In fact, it likely implies something has been missed. There may be similar constrains already implicitly applied.

In liberal theory, equality of process has traditionally been considered to equality of outcome(equity)

@rob I like the idea. Perhaps we could have a widget which allows this that is separate from the posts. Doing it from the posts would be sloppy and cumbersome. How hard would to be to add a polling feature?

@andy-dienes said in An Argument for MES:

there are basically two ways to think about proportionality of scored ballots. The first is a proportional distribution of utility, so two quotas of 0.5 is worth the same as one quota of 1.0. The second is basically thinking about quotas in whole numbers of voters treating the scores more or less like preferences, and so in some sense this is a proportional distribution of influence.

There is also a third. That is how much of your ballot/vote power you are willing to give up to see each winner win.

I would say that 1 is needed and obvious. 2 and 3 are incompatible because they are both about how you set a metric on the scores. SSS gives you 1 and 3 but MES gives you 1 and 2.

3 is basically vote unitarity.

@marylander said in Proportionality Guarantees of Allocated Score (approvals):

That would be useful. How do you decide whom to give weight back to? Is it even across the ballots?

I sent you an email. Let me know if you don't get it.

Hi @marylander,

In a chat with @Andy-Dienes the other day we came up with a new idea which is somewhat like what sequentially Shrinking Quotas does. There are are least two ways to implement it but the way I like best is as follows:

• It is the same as SSS except if there is a shortfall in reaching a quota to spend

• In that case you ADD some amount of "Ballot Weight" such that the "weighted Ballot" when summed for the winner is exactly a quota

It is doing the same thing as SSQ except that instead of changing the quota size to achieve the goal it it changes every bodies amount of ballot to spend. This gives voting power to those who will elect a candidate in subsequent steps but also to those who are already exhausted. Voters can come back from exhaustion. It gives the same result as SSS in most cases. I can give code if you would like.

I think it is actually doing what the true intent of SSS is better than SSS. That intent is to elect a utilitarian winner then adjust every bodies ballot weight "fairly". I tried to formalized "Fairly" with the concept of Vote Unitarity but I think I originally missed something. I think it is important to only subtract away the amount of influence they used to elect the winner. In the case of surplus the amount is reduced proportionally to that influence. In the case of shortfall I had thought it was fair to just take it all since that was the amount and no other group was going to put up that much for another candidate. However, This short-changes the prior winner and people with overlapping preferences. Since in the case of a shortfall I am effectively giving them ballot weight I need to give that amount to others.

Do you have thoughts on this idea? I can add code of you want.

I believe an earlier iteration of AS did this same thing, but it led to a monotonicity failure, so that failure was resolved by sorting voters by weighted score.

Correct but not a monotonicity failure on the score. It was more like a vote management vulnerability.

I did notice general patterns like throwing out a lot of score information during the reweighting did not affect quality much and made the rules much more robust to different preference distributions, including ad-hoc strategic ones.

This also implies you get the same results between two situations when there is a nuanced difference in preference. I think this is a tradeoff which would be hard to distinguish between.

To me, one of these score PR variants > STV, but nonetheless STV >>> single winner.

Single winner STAR is better if you care more about local representation than PR. In places like Canada with large sparsely populated areas you could end up with 5 member districts the size of Europe.

While I can prove a proportionality degree of (ℓ - 1)/2 for EPA, the proof relies on equal payments and I do not know how to get the result for AS

But AS could perform the same? Based on the similarity I would expect it to perform similarly.

Qualitatively, it just seems more fair that voters approving the same winner should all pay the same. This is corroborated by the many nice theoretical properties of MES.

They only differ when there is a surplus. In AS there is a threshold on score given. Above the threshold everybody pays the same (ie their whole ballot). Below the threshold everybody pays 0 even if they scored the winner. The people on the threshold pay an amount to match the quota. This does not seem unfair to me. The middle group pays some amount in the middle. In EPA the difference is that the above threshold group and the threshold group are treated the same, right? There can still be people who scored the winner who pay nothing, right? It does not seem clearly true that one method is more fair than the other as long as the distinction for how much somebody pays is based on their level of endorsement for the winner.

This is also one of the main reasons one might prefer either of EPA/AS over MES/SSS since the latter have an incentive at every point.

@Jameson-Quinn Made this point and it was ultimately why Equal Vote chose to endorse AS over SSS. This argument relies on the fact that a voter will actually be able to do such a calculation successfully. Or at least believe that they can. I am unconvinced. In fact I would argue the opposite. Since AS and EPA have major thresholds and somebody could allocated their whole ballot, they may be incentivised to put all their 1s and 2s to 0. In SSS you could only ever spend 2 on a 2 and 1 on a 1 so you are guarded from over spending. Voters will likely not behave rationally so much of it will come down to messaging anyway. Is it easier to explain to voters why they should vote sincerely in one system based on its mechanics. I would argue the mechanic in SSS does this but I am biased.

The above two intuitions are not just fantasy; I corroborated these experimentally across many preference profile distributions and strategy heuristics.

Can you give more detail? If you are saying that you have accurately simulated strategy then I am not going to believe you.

In fact, experiments were one of the main ways I landed on EPA before looking at theoretical guarantees. Empirically EPA returns better results than AS basically across the board on every metric besides total utility. In particular, the variance of utility tends to be significantly lower on instances where they disagree. While the axiom might be 'equal payments' for mostly qualitative reasons, the experiments suggest that this is a good axiom to take.

This work also included SSS and MES right? The simulations were based on my code from the "wolf Committee" right? Would you like to spend some time going through this on zoom?

variants of STV like Meek's (used in New Zealand) are really heinously complicated. Did you know it relies on iterating an optimization program until an arbitrary tolerance level is reached? Imagine if we could get away with that, I'd have a bunch more methods I'd like to suggest...

I think there needs to be a clean way to explain the system even if it is not 100% accurate to the final implementation. In campaigns, STV advocates rarely even mention surplus handling. To be acceptable a system needs to be able to be explained simply and the justification needs to be intuitive. I think MES could be acceptable if somebody came up with a good way to simply explain the selection mechanism.

Anyway, that's just to say if your main goal is to shift reform effort away from STV, I would not focus on elected outcomes because in my opinion the elected outcomes compared to other PR rules (preference profiles held equal) are fine.

The goal is not to move away from STV just because I hate STV. The goal is to offer a system which is monotonic, has a simple ballot to fill (ie not rank), can express level of endorsement (ie score) and gives something close to justified representation or sable winner sets. STV fails all these. I do not want to remove STV from its position as favourite PR system for any reason other than that it is subpar. I realize that in the majority of cases it does not matter but I think democracy is something where it really matters to be precise.

candidate strategy; right now it seems that parties just throw as many candidates on their list as possible in the hopes that a voter will like one of them and rank the whole list. In something like EPA/SSS/MES/AS, this will backfire for the voter (because they fail later-no-harm), so there will likely not be as much of a clone-positive incentive.

I do not understand this. Score systems are clone proof in the sense that your score for one candidate does not restrict the score for another. Are you saying that a party has incentive to put so many candidates that the candidates from another party are never reached when eliminating? This just points out another issue with STV. While it is technically non-partisan, in practice a bit of partisanship sneaks back in. Furthermore, the complexity of ranking incentivises people to "vote above the line" in Australia which reduces it to Party List. Only score systems allow independents to be free of parties. There are no modern examples of score systems but the theory is that they will lower partisanship via that mechanism.

the voter experience

Scoring is simple and faster than ranking.

STV is basically PR enough. I do not think that we will convince anybody to abandon it because it is not quite as PR as some of the score systems. STV is bad for other reasons. Some are listed above. If we can agree that STV is bad and there are systems which are better in all aspects then the problem becomes choosing between these other systems. This is the problem I am trying to solve. I believe the AS/EPA/SSS/MES area of models is the right one to look in. I do not think Thiele (RRV/SPAV) type systems are.

What Equal Vote did was to to rebrand AS as STAR PR. This way if a tweak like EPA turns out to be better then we can just pivot to that. This is sort of what is done with STV. It is not a single rule but a class of rules.

However, we still need to agree on a specific implementation and be able to justify it to the public.

I think it makes a lot of sense to restrict the space of these rules to those that have good theoretical guarantees on approval ballots, especially since it is a common heuristic that strategic voters will always min-max.

That makes sense to me

chaotic behavior exhibited by Allocated Score

Do you have some examples of this? I have not seen that work.

Not to nitpick, but the utility expressed definitely affects the reweighting! Just, it is converted to a binary value “is above the threshold.” Also note that due to the way skipped ratings are handled, it’s not quite the same as just treating the ballot like a ranked one.

OK, point taken but the point still holds. A lot of the information expressed on the ballot it obscured. I like the MES and SSS handling of score much better.

I agree that this is undesirable, but in the same sense that Perfect Representation is not always achievable, neither is it possible to only exhaust voters for their favourites. The alternative is to sometimes have broad swaths of voter budget go unspent; this is the approach that SSS takes—which has some benefits, most notably that of a more proportional distribution of welfare—but in my view it has also drawbacks in that voters will not pay equal amounts for their winners (aka less proportional distribution of influence),

This is sort of the trade off I was talking about. I am trying to think more in terms of public outreach and referendums. If the choice of "unspent budget" vs "Spend more than you score" translates to welfare proportionality vs influence proportionality that is worth highlighting. The public will only have an opinion on the first tradeoff because the second is too technical.

In the end the goal is to move the reform effort away from STV to a better system. I think any of Allocated Score, EPA, SSS or MES would be preferable to STV but it can be the case that too many options is a problem. If we knew what axioms the public really cared about we could try to come up with a proposal which we could all agree on.

There are many slight variants of Allocated Score. It is very hard for me to know which I like best unless there is a axiom I like which constrains the options to one. So what is the choice being made which turns Allocated score into EPA/