2011/3/18 Kevin Venzke <[email protected]> > Hi Jameson, > > --- En date de : *Ven 18.3.11, Jameson Quinn <[email protected]>* a > écrit : > > > Great results. > > I think it would help if you gave the SCWE of each method above the table, > and the SCWE of each line after that line. That way, we could see which > strategies were causing the problems with SCWE. Also, if you give further > scenarios, it would be great to see the results sorted by SCWE. > > Well, I tried to sort them thematically this time. I wasn't going to > discuss scores at all > at first, as there are just too many things I could say. > > One thing that strikes me is that often the methods with strategy > vulnerabilities were > better anyway, in this scenario. Sincerity doesn't necessarily translate > to quality. >
Would you say that that holds for dishonest strategies (C, B) or only semi-honest ones (M, T)? > > I can understand wanting to understand the outcome of each "line" though... > I'll have > to think about that. > > > I would be interested to see results for MCA runoff methods with this. The > possibilities are: > MCA-Runoff-approval - runoff if tied median, two candidates with highest > portion at median advance (or highest approvals if failed majorities) > (I suspect the top result for this would be ---TTTT, with very high SCWE) > > MCA-Runoff-preferred - as above, two winning candidates with highest top > ranking advance. > (I suspect that the top result would be MMMTTTT, with high SCWE) > > > Ok, I can add these. I think there is a large Condorcet advantage to the > runoff methods. > I do wonder about the clone issue though. It won't show up in this setting, > but if there > were no candidate limit candidates might end up nominated in pairs. > These methods do have a problem with clones. That's why I came up with the MCA-Asset methods; I think they'd do better against clones. > > > Both of those systems will generally agree with the corresponding MCA-Asset > version. The exception is that MCA-Asset will almost always elect C if B is > eliminated (ineligible for transfers), while MCA-Runoff will tend to elect A > in that situation. That's because B will transfer votes to C even though > some of those original voters might have preferred the less-extreme A. Since > both of these results are probably Condorcet failures anyway, the only > important difference resulting would be if under MCA-Asset, C voters were > more inclined to truncate, while under MCA-Runoff, A voters would do so. > However, since the other side always has a defense, I don't think either of > those would hurt the SCWE. Still, it might be worth simulating MCA asset > (assuming that B would always choose to transfer votes to C, and C and A to > B; and that A would transfer votes to B if they could and C couldn't, that > is, that A would believe the implicit threat of B to transfer to C.) > > > It is probably possible to do this for spectrum-based scenarios. I can't > remember > what the conditions are for this to happen under that method; I wonder if > you have it > handy. > By "this", I assume you mean vote transfers? If there is a median tie, then candidates can "transfer" their votes to to any other candidate who has a higher [stat of interest], where stat of interest is defined as Preferrals (see runoff-preferred) or Approvals (see runoff-approved). If A transfers to B, all ballots count B at max(A,B). If this does not resolve the election, then the winner is the member of the post-transfer tie with the highest post-transfer stat of interest. I believe you could use "asset" for any scenario, by assuming that the candidate's preferences are the same as those of the average of the voters who rank that candidate top. > If you're adding in these methods, you should add Majority Judgement as > well (eliminate median votes to break ties). This would probably come out > the same as MCA, but it is not quite identical, so it would be good to > confirm that. > > I'm not sure I have understood how this method works. Can you describe it? > Say A gets (Preferred/approved/unapproved) (20/50/30) and B gets (30/30/40). Both are median approved. Eliminate 20 median votes from each and you get (20/40/30) for A - still median approved - but (30/10/40) for B - rounding down, that's median unapproved. So A wins. (Note, elimination can shift median in either direction to break the tie.) This is not my proposal, but the idea from the book Majority Judgement. > Anyway. As to your actual results, it seems to me that the "good" methods > are the ones above 95%. Out of that set, it seems to me that it's clear that > MCA and Bucklin are the simplest methods to explain to voters. (Of course, > the MCA-runoff and -asset methods I propose are complex, not simple). > > So, I'd like to see someone make a good argument against MCA being the best > practical single-winner reform, for combination of simplicity and strategy > resistance. There may be such an argument which I'm just too biased to see. > If not... well, all y'all can unite under my banner at last :). > > > Well, we need to do more scenarios. I don't know if my first post, around a > week ago, > made it to the list. But (assuming I'm looking at the right Excel file at > the moment) > MCA placed fifteenth there, after methods like DMC and margins. > > In a non-spectrum-based set of trials, MCA was bottom half. The best SCWE > was > actually TTR. I tend to think the quality of MCA etc. depends on the voter > preferences > being distributed in a certain way. If presence or absence of a top-slot > majority doesn't > inform much in the given scenario, it will boil down to Approval. > > Plus sincere Condorcet efficiency is just one thing. We could talk about > election of > utility maximizers, average utility, Condorcet losers, utility minimizers. > With all voters strategic, I believe the first two of those metrics will just be noisier versions of SCWE. (I don't know, or honestly care much, about the latter two "worst-case" metrics, because I think they will be acceptably small under the methods I care about.) > I'm also > concerned about the possibility that some methods just won't support three > candidates > in practice. That may not be relevant to MCA though. > > My initial bets are on AWP implicit because I don't remember ever seeing it > place badly, > so far. > Very interesting. Do you think AWP-implicit-minimax is an acceptable substitute for beatpath, etc? (Because AWP is tough enough to describe with just minimax). And have you tried 3-rating CWP? My feeling is that 3-rating levels is sometimes the sweet spot, like 2 and infinity, and unlike any other number. Jameson
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