<div dir="ltr"><div class="gmail_default" style="font-family:"times new roman",serif">Could someone add a writeup of Majority Judgement to the wiki?</div><div class="gmail_default"><font face="times new roman, serif"><a href="http://wiki.electorama.com/wiki/Category:Single-winner_voting_systems">http://wiki.electorama.com/wiki/Category:Single-winner_voting_systems</a></font><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Sep 22, 2016 at 5:23 AM, Kristofer Munsterhjelm <span dir="ltr"><<a href="mailto:km_elmet@t-online.de" target="_blank">km_elmet@t-online.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On 09/22/2016 03:38 AM, Jameson Quinn wrote:<br>
><br>
><br>
> 2016-09-21 18:59 GMT-04:00 Kristofer Munsterhjelm <<a href="mailto:km_elmet@t-online.de">km_elmet@t-online.de</a><br>
</span>> <mailto:<a href="mailto:km_elmet@t-online.de">km_elmet@t-online.de</a>>><wbr>:<br>
<div><div class="h5">><br>
> On 09/06/2016 01:29 AM, Jameson Quinn wrote:<br>
> > ...<br>
> > If that's true, then there's some kind of threshold of number of grades,<br>
> > below which there aren't enough grades for the ballot format to<br>
> > encourage grading against a common standard. So three-slot methods would<br>
> > have to be tested to see if voters would vote grading-style or<br>
> > relative-rank style with three grades, or if three grades are still<br>
> > too few.<br>
> ><br>
> ><br>
> > Personally, I'd guess that three would be enough. I think the four most<br>
> > common voting heuristics, in descending order, would be:<br>
> ><br>
> > First, as I've said: approve of one, disqualify greater evil among the<br>
> > frontrunners and any evils greater still.<br>
> ><br>
> > Second: Approve of one, disqualify both frontrunners.<br>
> ><br>
> > Third: if one side of the left-right divide got used to habitually<br>
> > losing, the centrists among them might begin to extend approval all the<br>
> > way to the most-centrist on the other side.<br>
> ><br>
> > Fourth: Approve of one, disqualify unqualified/unserious candidates.<br>
> ><br>
> > Any of the heuristics above would tend to lead to a "successful"<br>
> > resolution of the Chicken Dilemma.<br>
><br>
> That's kind of going into the domain of "manual DSV", though, which I'm<br>
> not as much a fan of. MJ has this going for it that there are ways for<br>
> honest voters to vote as long as the categories are well-defined.<br>
> Approval is a *lot* muddier, because it's much less certain that honest<br>
> voters can divide the candidates into "I like these" and "I definitely<br>
> don't like these". Three-slot methods could work if the heuristics are<br>
> common and intuitive enough, but they're kind of in-between MJ's<br>
> expressiveness and having Approval's manual DSV needs.<br>
><br>
><br>
> Median-based methods, especially those which break ties using<br>
> above-median votes, can do well with chicken dilemma scenarios. The<br>
> flipside of this is that in order to handle center-squeeze scenarios,<br>
> they require the voters who favor the centrist CW to put all other<br>
> candidates below the winning median; for safety, at bottom-rating.<br>
><br>
> I think that's somewhat plausible as a naive strategy ("Since I'm<br>
> Center, I think Left and Right are equally bad, so even though I don't<br>
> hate them as much as they hate each other, I might as well put both of<br>
> them at bottom rank"). I also think that when Center voters don't so<br>
> strategize, the outcome is not too bad; generally, that will tend to be<br>
> in cases where Center might even have lost a score election, and the<br>
> candidate who beats Center might even be the utility winner or at least<br>
> close to it.<br>
><br>
> But yes, there is this much "manual" strategy necessary, and I don't see<br>
> any way around it. I think a system can't be robust to strategy in both<br>
> Chicken and Center Squeeze scenarios, and I'd rather get Chicken right<br>
> in spite of some strategy (and thus not encourage strategies which, when<br>
> over-applied, can end up electing the CL) instead of getting Center<br>
> Squeeze right without any strategy.<br>
<br>
</div></div>Do you think there's a way to formalize vulnerability to center squeeze?<br>
I imagine there would be two criteria:<br>
<br>
- No center squeeze outright (e.g. IRV)<br>
- No center squeeze with strategy<br>
<br>
And I suppose for the latter, you *could* make a rather heavyhanded<br>
criterion saying something like: if C is center and strategy can make<br>
not-C win but not make C win, then it's vulnerable to strategic center<br>
squeeze...<br>
<br>
but that doesn't feel very elegant. Any ideas? Perhaps something<br>
involving votes being drawn from a spatial model so that the idea of<br>
"center" is relatively apparent?<br>
<br>
The point is that if we had a formal model, I could check what methods<br>
pass the criterion (or often pass it), and then see if there's anything<br>
that both passes CD and whatever it ends up being.<br>
<br>
Do you think hybrids that use both Condorcet and positional data (like<br>
my fpA-fpC stub method or Benham/Woodall methods) pass both CD and<br>
center squeeze? They do at least elect the centrist when there is a CW.<br>
I guess the question would be how badly they degrade when there is no CW.<br>
<div class="HOEnZb"><div class="h5">----<br>
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</div></div></blockquote></div><br></div>