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

[Michael Ossipoff]

On Mon, Dec 19, 2016 at 9:50 PM, Juho Laatu <juho.laatu at gmail.com> wrote:

> On 20 Dec 2016, at 01:33, Michael Ossipoff <email9648742 at gmail.com> wrote:
>
>
> We have no reason to worry about offensive strategy in CIVS polls.
>
> And so MAM is the best choice for CIVS polls. MAM is one of the
> rank-counts that CIVS supports.
>
>
> Ok, MAM is a quite decent method. If strategic voting is minimal, I guess
> you pick the method that gives best results with sincere votes. I'm still
> lacking good understanding of why exactly MAM would produce best winners
> with sincere votes.
>

MAM is the ideal, among the methods that look only at pairwise-defeats and
their strengths, and that comes from MAM's definition:

MAM:

A pairwise defeat is affirmed if it isn't the weakest defeat in a cycle
whose other defeats are affirmed.

A alternative wins if it doesn't have an affirmed defeat.

[end of MAM definition]

It couldn't get any more minimal & ideal than that. MAM (unlike Beatpath,
etc.) never unnecessarily disregards a pairwise defeat (by electing someone
who has the defeat).

In a method based only on pairwise defeats & their strengths, the only
thing that should nullify a defeat would be if that defeat is the weakest
in a cycle, and if the other defeats in that cycle aren't nullified in that
way.

Additionally, MAM has excellent burial-deterrence & thwarting. That's why I
use MAM, in Pairwise-Winner(MAM,  Smith,MMPO).  ...for MAM's
burial-deterrence. But MMPO, & not MAM, is chicken-dilemma defection-proof,
which is why I like to combine both of their strategic advantages, in
P(MAM,  Smith,MMPO), for polls with possibly offensive-strategic voters.



>
> When offensive strategy is used against the CWs, s/he'll be in the voted
>> Smith-set. That's a good reason to elect from the voted Smith-set, so that
>> the CWs can maybe be rescued.
>>
>>
>> In theory that might save the CWs in some very rare cases.
>>
>
> I can't say why it's important to guarantee that the winner is in the
> voted Smith-set, other than that it confers compliance with various
> criteria, including Mutual-Majority.
>
>
> That's a good answer since there are situations where one can justify
> electing from a Smith set that consists of very similar minded clones. The
> top cycle can be sincere or strategic. The same matrix can however probably
> be also a result of sincere votes where the Smith set candidates are not
> clones but a much more competitive group. In such cases it could make sense
> to elect outside the Smith set. One key point here is that information in
> the matrix is limited, and it is impossible to say if there are clones, and
> which preferences are strong and which ones weak.
>

But, with pairwise-count methods, the number of people voting a preference
stands-in as an indication of its importance, imperfect though that may be.

It's important to find out the CWs, because that's the best that anyone can
expect to get. Truncation-proof MAM & MMPO still elect the CWs when someone
truncates it. MAM's deterrence of burial, improves the likelihood of
electing the CWs if there is one--& there usually is one.



>
> But, because one member of the voted Smith set will be the CWs, if
> truncation or burial is being attempted against it (neuter gender because
> I'm talking about poll-alternatives) then that means that disqualifying
> non-members of the voted Smith-set narrows the field in a way favorable to
> the CWs.
>
>
> It is not possible to tell if there was a CWs.
>

True, but if there is one, then it will win even if there's a
truncation-caused cycle. Truncation-proofness is important, even in a
sincere electorate, because truncation can be non-strategic (lazy, hurried,
principled, etc.).


> The top loop can be sincere as well (or a result of various good and bad
> strategies). And the best sincere winner might be also outside the Smith
> set.
>

Certainly, because it would be possible for the alternative satisfactory to
the most people to be outside the Smith set. But probably it will usually
be the CWs, or in the sincere Smith set if there isn't a CWs.


>
> Note that electing outside the Smith set may sometimes also help us, e.g.
>> by making strategic plans void by not electing the (possibly strongly
>> top-looped) favourite of the strategists.
>>
>
> Maybe, but, by pairwise-count standards, electing from the Smith set keeps
> the winner among the pairwise publicly-favored candidates.
>
>
> I don't understand your definition of "pairwise publicly-favored
> candidates". Why can't candidates outside the Smith set be such candidates?
>

Because, pairwise is what the Smith set is about. Something outside the
Smith set might be more approved than the Smith set members, but it won't
be pairwise publicly preferred to them.


> I mean situations where the leading candidate outside the Smith set could
> lose by one vote to all the Smith set members. Losing only marginally to
> many candidates could be a better result than losing a lot to fewer
> candidates.
>

Sure, that could be argued on ethical grounds. But pairwise defeats are
what's important if you want to avoid an angry majority who prefer someone
else to the winner.

And the CWs is important to find, in polls, because it's the best that
anyone can get (unless they're a good offensive strategist, in an election
or poll using a method vulnerable to that strategy).


>
> Of course, in an election, when Approval elects the candidate approved,
> considered satisfactory by the most people, is probably more important than
> electing the CWs or from the sincere Smith-set.
>
>
> Also pairwise comparisons can sometimes lead to situations where best
> candidate (based on those pairwise comparisons) is found outside the Smith
> set. (see the marginal loss example above)
>

Yes. looking at the strength of pairwise oppositions instead of at pairwise
defeats. But the pairwise defeats have great importance in regards to
finding the best that we can get.



>
> MAM, by itself would surely, it seems to me, be the best way to find the
> CWs, for sincere voters.
>
>
> All Condorcet methods can find the CWs with sincere votes.
>

True, but truncation needn't be strategic, and so truncation-proofness is
important even with the most sincere electorate.

Besides, when MAM & Beatpath give different winners, MAM's winner pairbeats
Beatpath's winner by a factor of several to 1.  That's a result of MAM
disregarding as few pairwise defeats as possible.

[Replying farther down] :


>
> I'm sure there will always be some irrational behaviour, but that might be
>> just general noise, and would not influence the election. If some large
>> grouping will use some irrational strategy, and as a result will make the
>> outcome of the election worse from their point of view, maybe they will
>> learn and will vote rationally (sincerely or strategically) in the next
>> election.
>>
>
> If the CWs is  in your strong bottom-set, then burial, even when it risks
> electing a worse member of your strong bottom-set, isn't irrational, if
> there's _any_ chance of successfully changing the winner to someone in your
> strong top-set.
>
> If we were using Condorcet, and if the expected CWs were a Repugnocrat,
> I'd routinely use burial strategy, every time, in hopes of electing a
> progressive. That's good strategy.
>
>
> Ok, if your preferences are A >>>>> B > C, and your guess is that B is a
> CWs, then it would be quite risk free to try to create cycles. It is
> however quite possible that your vote will be part of the "general noise".
> Some C supporters could also compromise (= top rank B) if they believe that
> B's victory is not certain, and some B supporters could rank A lowest if
> they believe that many A supporters plan to bury B.
>


Sure, those are good defensive strategies against burial. But I don't care
which Repugnocrat wins. So if there's any chance that I can strategically
elect a progressive, I'd bury.

(Truncation wouldn't work in MAM, or MDDA, and it wouldn't work in MDDAsc
against someone who is majority-approved, when done by someone whose
candidate isn't majority-approved. And it wouldn't work in MAM, MDDA, or
MDDAsc against a candidate top-ranked by a majority.)




> Many A supporters would not like the idea of increasing the chances of C
> winning the election.
>

Yes, there are many Democrat-overcompromiser suckers.

P.T. Barnum, that great social scientist, pointed out that there's one born
every minute.



> Many voters would vote sincerely since that's what they believe is the
> right thing to do.
>

Voting in way that's more likely to elect someone who won't hurt a lot of
people is hardly unethical.


> There are so many parameters and uncertainty in polls that coherent
> strategic voting may not be common.
>

If Sleaze-Democrat isn't really the CWs, then youj're no worse off when you
bury hir. It just won't matter.

Burying someone in your strong bottom-set doesn't need good predictive
information.



> It may not be easy to get sufficient number of strategic voters to follow
> the plan.
>

Yes, no one should count on the situation improving, or a better world ever
somehow arriving.

But a plan would be something different from what I meant. I just spoke of
how _I'd_ vote.


>
> I have been asking for generic strategic guidance for Condorcet elections.
> I think you are close to proposing one rule here. Maybe something like "if
> you strongly dislike the expected winner, bury it under all such candidates
> that are not much worse than it".
>

Good enough.


> Maybe add "if some of your favourite candidates are expected to beat
>
 those candidates".

...or even if not.  Burial can elect someone pairbeaten by the CWs.

 Maybe you can improve my formulation of that possible strategic advice.
Maybe simulations could tell if that strategy does more good than harm

[endquote]

Strategy can't do any significant harm if the CWs is in your strong
bottom-set.

But I emphasize that I wouldn't expect that situation, because I give the
other votes credit for better judgement. Jill is the CWs in my poll at CIVS.



>
>
> after the election but only in the ballot when voting). This whole process
>> would be repeated few times.
>>
>
> But people would then be using counterstrategy agains the declared
> offensive strategy, and that would make it unrealistic, because in real
> elections, the voters might not be as adept at counterstrategy.
>
>
> But, ever since EM started, I've always felt that poll are super useful &
> valuable, as the only way to find out what it's like to use the various
> voting-systems. You probably know that I started lots of polls at EM.
> They've fallen out of fashion, and I consider that regrettable, because you
> can't fully evaluate  & compare voting-systems without actually trying
> them. Voting in polls, and counting polls.
>
> So yes, I'm in favor of polls at EM. Regrettably no one else is.
>
>
> Yes, polls can be very helpful. And paper work sometimes too, if
> disciplined enough.
>
>  I have great trust on the skills of people on this mailing list, but so
>> far I have not seen any good strategic guidance for voters or parties in
>> real life Condorcet elections.
>>
>
> Well, I mentioned, above, that I'd routinely use burial strategy when the
> expected CWs is in my strong bottom-set, in an official Condorcet election.
>
>
> Yes. If you can, please upgrade my description above to something that you
> believe to be valid guidance to regular voters. (Alternatively you can give
> also strategic rules for parties, that may then give further guidance to
> their supporters).
>

My best suggestion would be to top-rank all of the progressive candidates
(or approve (only) them all, if the method is Approval).

In the very unlikely situation where the likely CWs is a Democrat, I'd say,
"Let's bury hir under the Repugnican."

>
> Here's another one that may work e.g. against some minmax style Condorcet
> methods. "If some unwanted party/grouping has numerous equally disliked
> candidates, rank them in a loop in alphabetical order, starting from a
> random candidate".
>

Sure, there's no reason to not try that, in the methods in which it could
work. Of course it wouldn't work in MAM. But it could work in the methods
that I like best for official elections.

Michael Ossipoff

>
>
>
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>
>
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