[EM] What are some simple methods that accomplish the following conditions?
stepjak at yahoo.fr
Tue Jun 11 17:30:16 PDT 2019
Le dimanche 9 juin 2019 à 21:20:34 UTC−5, C.Benham <cbenham at adam.com.au> a écrit : >Kevin,>>So to be clear the possible "complaint" some voters might have (and you think we should take seriously) is "We lied >and the voting method>(instead of somehow reading our minds) believed us".
A burial strategy has two scenarios that could give rise to a complaint. One is where burial succeeds. In that case the voters who complain aren't the ones who buried. The other scenario is where burial backfires. In that case it is, I guess, possible that actually *all* voters were using burial. So you may argue that they don't have a valid complaint. But implicit to my concerns is the premise that the voters are behaving rationally under the incentives of the method. If a method produces arbitrary results given rational voters then it will be hard to retain it. I think if it happens even once it will be a problem.
>So therefore it is good to have a less expressive ballot because that reduces the voter's opportunities to tell stupid >lies and if the method>is simple enough then maybe also the temptation for them to do so.
You're making it sound as though a simpler ballot just tricks people into not lying. Expressiveness isn't the point. The reason three-slot C//A (or implicit etc.) deters burial is that there is far more risk in trying it. It is highly likely to backfire no matter what other voters do. "Low expressiveness" of the ballot doesn't guarantee this and isn't a prerequisite for it either.
>But I've thought of a patch to address your issue. We could have a rule which says that if the winner's approval >score is below some fixed >fraction of that of the most approved candidate, then a second-round runoff is triggered between those two >candidates. What do you>think of that? What do you think that fraction should be?
I think there is some confusion here between what my issue is, and the voter complaints you asked about. While I think voters will be unhappy with a ruined election, ruining it is what reduces the burial incentive. If the risk outweighs the benefit then people won't do it. (That's an assumption.) This patch seems to remove the risk while leaving the benefit unchanged. Burial will ultimately do nothing, except to sometimes move the win from the CW to the AW. But that makes the potential gain even clearer: If the voted CW turns out to not be your candidate, you would have had a second chance at the win by voting instead to deny CW status to that candidate. If the voted CW *is* your candidate, then you're no worse off for using burial.
On 10/06/2019 9:57 am, Kevin Venzke wrote:
>>I don't think it's ideal if burying X under Y (both disapproved) can only backfire when Y is made the CW. >>
>Why is that?
Because I think if voters decide to attempt to prevent another candidate from being CW, via insincerity, there should be risks to doing that. Of course there is already some risk. But if you "knew" that a given candidate had no chance of being CW then there would be nothing to lose in using that candidate in a burial strategy.
>The post-election complaint (by any of the voters) would be .. what?
For either a successful burial strategy, or one that backfires and elects an arbitrary candidate, I think the possible complaints are clear. Maybe someone would argue that a backfiring strategy proves the method's incentives are just fine. But that wouldn't be how I see it. I think if, in actual practice, it ever happens that voters calculate that a strategy is worthwhile, and it completely backfires to the point that everyone would like the results discarded, then that method will probably get repealed.
>If you don't allow voters to rank among their unapproved candidates then arguably you are not even trying to elect the sincere CW.
>Instead you are just modifying Approval to make it a lot more Condorcet-ish.
Not an unfair statement. If you require voters to have that much expressiveness then you can't use implicit.
To me, the motivation for three-slot C//A(implicit) is partly about burial, partly about method simplicity, partly about ballot simplicity. C//A(explicit) retains 1 of 3. (Arguably slightly less for the Smith version.) Possibly it has its own merits, but they will largely be different ones.
>A lot of voters like relatively expressive ballots. I think that is one of the reasons why Approval seems to be a lot less popular than IRV.
I have no *inherent* complaints about the ballot format of explicit approval plus full ranking.
Le jeudi 6 juin 2019 à 21:03:19 UTC−5, C.Benham <cbenham at adam.com.au> a écrit :
Specifically should "positional dominance" have the same meaning whether or not the method has approval in it?
If the voters all choose to approve all the candidates they rank, then yes. (For a while I was wrongly assuming that Forest's suggested
default approval was for all ranked-above-bottom candidates, but then I noticed that he specified that it was only for top voted candidates).
One of my tired examples:
Assuming all the ranked candidates are approved, C is by far the most approved and the most top-voted candidate.
Normal Winning Votes (and your idea 2 in this example) elect B.
I will go easy on these methods over failing MD, because it happens when some of the majority don't approve their common candidate.
For me this this type of ballot avoids the Minimal Defense versus Chicken Dilemma dilemma, rendering those criteria inapplicable.
The problem has been that we don't know whether the B>C voters are thinking "I am ranking C because above all I don't want that evil A
to win" or "My C>A preference isn't all that strong, and I think that my favourite could well be the sincere CW, and if C's supporters rank
B above A then B has a good chance to win. But if they if they create a cycle by truncating I'm not having them steal it".
With the voters able to express explicit approval we no longer have to guess which it is.
I don't think it's ideal if burying X under Y (both disapproved) can only backfire when Y is made the CW.
Why is that? The post-election complaint (by any of the voters) would be .. what?
If you don't allow voters to rank among their unapproved candidates then arguably you are not even trying to elect the sincere CW.
Instead you are just modifying Approval to make it a lot more Condorcet-ish.
A lot of voters like relatively expressive ballots. I think that is one of the reasons why Approval seems to be a lot less popular than IRV.
On 6/06/2019 5:34 pm, Kevin Venzke wrote:
I've been short on time so I don't actually have much thought on any of the methods, even my own.
I suppose Idea 2 is the same as Schwartz-limited MinMax(WV) if nobody submits disapproved rankings. I'm not sure if it makes sense to reject the method over that. Specifically should "positional dominance" have the same meaning whether or not the method has approval in it? As a comparison, I will go easy on these methods over failing MD, because it happens when some of the majority don't approve their common candidate.
I would have liked to simplify Idea 2, but actually Forest's eventual proposal wasn't all that simple either. As I wrote, if you add "elect a CW if there is one" it can become much simpler, so that it isn't really distinct from Idea 1. I actually tried pretty hard to present three "Ideas" in that post, but kept having that problem.
I posted those ideas because I thought Forest posed an interesting challenge, and I thought I perceived that he was trying to fix a problem with CD. That said, I am not a fan of Smith//Approval(explicit). If all these methods are basically the same then I probably won't end up liking any of them. I don't think it's ideal if burying X under Y (both disapproved) can only backfire when Y is made the CW.
Le mercredi 5 juin 2019 à 21:26:23 UTC−5, C.Benham <cbenham at adam.com.au> a écrit :
I didn't comment earlier on your "idea 2".
If there no "disapproved rankings" (i.e. if the voters all approve the candidates they rank above bottom),
then your suggested method is simply normal Winning Votes, which I don't like because the winner can
be uncovered and positionally dominant or pairwise-beaten and positionally dominated by a single other
On top of that I don't think it really fills the bill as "simple". Approval Margins (using Sort or Smith//MinMax
or equivalent or almost equivalent algorithm) would be no more complex and in my opinion would be better.
I would also prefer the still more simple Smith//Approval.
What did you think of my suggestion for a way to implement your idea 1?
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