[EM] Voting-System Choice for Polls (Just one more thing I want to say)

[Juho Laatu]

> On 18 Dec 2016, at 08:05, Michael Ossipoff <email9648742 at gmail.com> wrote:
> 
> Before quitting EM & retiring from voting-systems, there's one more thing I'd like to say:
> 
> What's the best voting-system for polls?

Mostly exactly the same as for elections. Polls may however often be less competitive than elections. (Although some elections can be less competitive than some polls.) This means that you could emphasize performance with sincere votes more, and put less weight on performance against strategic voters.

> 
> Though FBC is important for official political elections

No, FBC is not important. It is important not to be vulnerable to "betrayal strategies", but that doesn't necessarily mean FBC compliance. :-)

> , I don't think it serves a purpose in polls, where the purpose is to get sincere rankings, and hope that people vote sincere rankings. In polls, the compulsion to favorite-bury is much less likely.

Often so.

> 
> As I've said, I haven't noticed any sign (top-cycles for 1st place) of strategy in polls.

Has somebody sometimes noticed a strategically generated top-cycle or any other cycle in any elections or polls?

> 
> I suggest that, for sincere electorates, MAM is the ideal best. That means it's best for polls at the Condorcet Internet Voting Service, where there's been no sign of strategy.

When strategic intentions are gone, or low enough, one should focus on which candidate is best according to the needs of the society. I have no good idea on what MAM tries to achieve (= what kind of winner to elect) with sincere votes. In some polls Range could be the best (if you want the winner to have high average support), or maybe Approval (= elect the most approved candidate) or some Condorcet (= elect the one who is preferred over the others) method.

> 
> But what if you're doing a poll among people who are highly involved in the subject that you're polling about, and have strong committment to some alternatives? Like, for example, suppose you're pollng at EM about voting-systems?

I guess you are talking about competitive polls here. I.e. EM members are expected not only to have strong opinions on the alternatives but also strong intentions to make their favourite win (by voting strategically).

> 
> Maybe some members of the electorate will resort to strategy. Especially if the electorate are a voting-system mailing-lislt.

Yes, sounds very competitive.

> 
> So you can't really be sure that there'll be no chicken-dilemma defection.

Among this group of people, I'm sure you couldn't be sure of anything :-) , and you should protect yourself against all possible strategies. Or at least against those strategies that EM people are likely to master. That is probably a smaller set than the largest set of all theoretically possible strategies. :-)

> 
> So maybe, instead of MAM, Smith//MMPO should be used.

Ok, now you are talking about highly competitive polls. Why did you introduce Smith set here? Is that to safeguard against strategies? I'm not knowledgeable enough to tell what kind of strategic threats Smith set would eliminate. Maybe you introduced it to have good performance with sincere votes.

This is a sidetrack, but I must note that I'm not a believer in Smith set. My opinion is that it tries to force linearity to group opinions. You can expect that (linear opinions) from individual voters, but in groups there's no need to assume that all the Smith set members would be better than the other candidates (with sincere votes). You can as well think than losses to other candidates are a bad thing, irrespective of whether they occur in cycles or not. Losses within a cycle could be considered worse than losses outside of that cycle.

> 
> It is automatically resistant to chicken-dilemma defection.
> 
> But, for burial, it isn't as good as MAM. With MAM, a candidate that you, & sufficiently-many others, don't rank can't beat the CWs by burial.
> 
> ...but it can in MMPO, though there's a lot of uncertainty & risk in trying burial in MMPO.
> 
> Maybe Smith//MMPO's reliable automatic chicken-dilemma protection is more important, because defection is easier & less drastic a strategy than burial.
> 
> But maybe MAM's better burial protection is more important, because burial temptation & opportunity is a lot more common than a chicken-dilemma situation.
> 
> My suggestion: Use both.
> 
> Do the count by Smith//MMPO, & by MAM. Of the winners by those 2 methods, the final winner is the one that pairwise-beats the other.
> 
> That's a solid good solution, because:
> 
> In the chicken-dilemma example, and also in a burial example, the intended victim of the offensive strategy pairbeats the perps' candidate.
> 
> So, declaring, as winner, the one of those 2 winners that pairbeats the other is definitely the best solution, if MAM & Smith//MMPO are the best choices, each of which offers better protection in different ways.
> 
> Of course, it's been pointed out that methods that elect the pair-winner, among the winners by 2 different methods, tend to fail FBC.
> 
> But FBC isn't needed in polls, where you want sincere ranking, not equal-top-ranking.

I'm not able to take position on how good that combination would be against strategies that might emerge among the EM list voters. The discussed environment is assumed to be very competitive, and I guess there's no difference any more on whether we had a poll or an election. Both would be competitive, and similar methods would be needed to make the system work.

Or actually I do believe that often we do not really need extreme defensive measures, and putting more emphasis on electing the best winner with sincere votes is possible. I mean for example that I have not seen any good general guidance (to regular voters with no exact knowledge on how other voters are going to vote) on how to vote strategically in some very basic Condorcet elections. My best guess is that even if EM list would vote on which single winner election method is the best, using Condorcet, I would not expect people to identify any good strategy that they could use to (effectively, intentionally) manipulate the results and change the winner from the sincere winner to some alternative that they like better.

For these reasons I tend to favour methods that are good with sincere votes, and that are designed to protect us only against some very basic and very obvious strategic voting opportunities. I'm somewhere at the level of "in most cases Condorcet is enough".

BR, Juho

> 
> Michael Ossipoff
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info

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