[EM] Bucklin/IRV hybrid? Motivated by MSV strategy

Wed Nov 2 15:14:20 PDT 2016

Chris--

I'd said:

> For #2, it really takes something with a lot of valuable &
> otherwise-unobtainable properties, to justify replacing Approval, Score or
> Bucklin with it.
>
> I suggest that only Plain MMPO qualifies.
>
>
You replied:

Say you ask people who are used to and/or like any of  Approval, Score,
Bucklin,  or  plurality (aka FPP) or Top-Two Runoff or IRV or Benham:

(a) Would you accept a method that in a 3-candidate election with 20
million voters can elect a candidate that is voted above equal-bottom
on only two ballots?

x: A
1: C=A
1: C=B
x: B

x = any number greater than 1.   MMPO  elects C.

(enduote)

1. When I asked who is wronged, you said that the A voters are wronged,
because, rightfully, it should be an A&B tie, and the A voters should have
a 50% probability of their favorite winning.

My answer to that was & is that the A voters have indicated that they don't
consider B any better than C. They're indifferent between C and the other
candidate whom they'd like to have a 50% probability of winning. Wronged?
Sure. Significantly-wronged? No. It certainly can't be called an outrage.

2, You make it sound as if what happened in that example is entirely the
fault of the voting-system, and maybe the two A=C and B=C voters..

But it was done by the all A voters and B voters. In a method known to look
only at pairwise opposition, those voters ensured that A & B will have as
much pairwise opposition as anyone can have, because they refused to rank
eachother's candidate over C.

Refusal to co-operate with a rival can be a mistake in any method. It's
hardly surprising if it's a mistake in MMPO too.

So don't let the A voters & B voters convince, you when they whine about
that result.   ...the result of their refusal to co-operate with eachother.

Think of it as the chicken-dilemma defection-blunder magnified.

Ridiculous result? Sure. ...caused by ridiculous voting.

...in an implausible example.

--------------------------------------------------------------------------------------------

That being said, I admit that the bad-example shows that MMPO has a
wrong-looking-result-vulnerability.

They go with methods that have deluxe properties. What else is new.

The problem is that, of course, MMPO gets its unqualled
properties-combination by looking only at pairwise opposition.

For one thing, that means that it disregards how much positive support a
candidate has. So it was possible to write a bad-example in which someone
wins with practically no positive support...without that example's result
seriously wronging anyone.

Also, because it's _pairwise_ opposition, a candidate with two factions
each ranking a different candidate over C, the method ignores the fact that
C has _two_ candidates ranked over hir by a large number of voters, whereas
A & B each have only one candidate ranked over them (by just one more
voter).

MMPO doesn't count how many candidates are ranked over C, or the total
number of voters who rank C lower. Thereby we get the wrong-looking result
where C has both of the other candidates ranked over hir by a lot of
people, but still beats A & B, each of which have just one candidate ranked
over hir--by one more voter..

These are obvious inevitable results of looking only at pairwise opposition.

But, even with those wrong-result vulnerabilities, the resulting
bad-example doesn't significantly wrong anyone.

Even though no serious wrong is done by those wrong-looking results, what
can be done to avoid them?

* Rank some in-between compromise candidates over the worst one, ok? Is
that too much to ask?

In that way, you rank eachother's candidate over the worst one, giving hir
more people ranking those candidates over hir, to give hir more pairwise
opposition than the candidates you like better.

Set your rivalry aside and do that.

* Don't allow write-ins.  Or, if you do allow write-ins, make sure that you
rank compromises, not just your favorite, so that you're all voting
eachother over whatever unknown write-in comes along, so  that hir
individual pairwise oppositions won't be less than those of the candidates
you like more..

All the rank methods have strategy problems, to go with the deluxe
properties that they bring. The more deluxe properties, the more kinds of
wrong-looking results are possible. You get what you pay for.

So you deal with those special  vulnerabilities, as the price of the deluxe
properties.

Michael Ossipoff

(b) Do you think it is fair and sensible that a voter who is only
interested in getting their favourite elected can increase the chance of
that
happening by fully ranking (below top) all the other candidates at random?

What response do you think you will get?

I don't live in the US, but I would think that most people wouldn't even
believe that question (a) is serious, and that anyone who tries to
tell them that that example only "looks bad" would blow their credibility.

Chris Benham

Jameson--
>
>
> On Sat, Oct 29, 2016 at 11:16 AM, Jameson Quinn <jameson.quinn at gmail.com>
> wrote:
>
>>
>> ....Here's my "ideal characteristics" for a political single-winner
>> election system, more or less in descending order of importance:
>>
>>    1. FBC
>>
>>
> Yes, I consider FBC to be #!.
>
>
>>
>>    1.
>>    2. Handles center squeeze (ie, some form of weakened Condorcet
>>    guarantee that's compatible with FBC)
>>
>> But maybe the goal of electing the CWs unnecessarily complicates votiing.
> Maybe someday, there won't be a bottom set, for most voters, and, with
> honest elections & honest, open media, it will be clear who's the CWs. But
> now, Approval's best strategy doesn't require that. Brams pointed out that
> Approval's results can be better than the CWs.
>
> But, when it's desirable to elect the CWs, and it isn't obvious who's the
> CWs, then the wv methods, and methods with wv-like strategy (such as MMPO),
> are the methods that make it easiest to protect the CWs.
>
> Also, it should be noted that you can't be sure how often there will be a
> CWs, under different and better conditions.
>
>
>>
>>    1.
>>    2. Relatively simple to explain
>>
>>
> Approval & Score are easy to explain. I've had conversations in which only
> Approval & Score were accepted as being plain & un-elaborate enough to be
> acceptable..
>
> You know that SARA & XA are complicated and not easy to explain. I've
> tried explaining them.
>
> MMPO?:
>
> "The winner is the candidate who has fewest people voting someone else
> over hir."
>
> {...some same other candidate)
>
>>
>>    1.
>>    2. Minimal strategic burden
>>
>>
> We often hear it said that Approval has a large strategic burden, but, for
> most people, with our current candidate-lineup, there's nothing difficult
> about it: Approve (only) the progressive candidates. That's optimal for
> most people.
>
> And if the time comes when, for most people, there isn't a bottom-set,
> then that will be a happy circumstance, in which it doesn't matter terribly
> anyway, which candidate wins.
>
> In such conditions, with honest elections and honest, open media, it will
> likely be pretty obvious who's the CWs, and, in the absence of
> tep-set/bottom-set, the best strategy will be to just approve down to the
> CWs.
>
> And, if there were no bottom-set, and if it happened that it _wasn't_
> clear who the CWs was, and it was 0-info, then it would just be a matter of
> approving down to the expected winning merit-level. Maybe, under those
> conditions, that would be the candidate-mean.  Or maybe (as now)  the
> estimated mean merit of what voters want (which can be estimated by the
> candidates' merit-midrange, if the election is 1D.  ....but it might not
> remain 1D under different and better conditions).
>
> ..but I repeat that, with only your former top-set remaining as winnable
> candidates, it won't make as much difference which one wins anyway.
>
> People often consider Approval voting more difficult than it is.
>
>
>
>>
>>    1. Summable (ideally O(N), no worse than O(N²) in practice, though I
>>    might accept some special pleading for the use of prior polling to reduce
>>    to O(N²).)
>>    2. Handles CD, or at least, CD offensive strategies don't in practice
>>    mess up the center squeeze properties.
>>
>>
> MMPO meets Weak CD.
>
>
>>
>>    1.
>>    2. Some arguable track record
>>
>>
> Of course at EM we discuss two completely separate and different method
> proposal choices:
>
> 1. Proposals to electorates who have only had Plurality.
>
> 2. Later proposals to replace one better voting system with another.
>
> If we're talking about #1, then there are only a few to choose from:
>
> Approval, Score, and Bucklin.
>
>
> I suggest that all 3 of those should be offered to initiative-proposal
> committees, and that the public should be polled, or consulted in
> "focus-groups", regarding which of those 3 methods they'd  accept
>
>
> For #2, it really takes something with a lot of valuable &
> otherwise-unobtainable properties, to justify replacing Approval, Score or
> Bucklin with it.
>
> I suggest that only Plain MMPO qualifies.
>
>
>
>
>>    1.
>>
>>  Approval does well on 1,3,4, and 6, is OK on 2, and bad on 4 and 5.
>>
>
>
> No. Contrary to what we so often hear, Approval doesn't have a high
> strategic burden, as I discussed above.
>
> Other than MMPO's CD, improvements over Approval by more complicated
> methods are illusory.
>
> And your standard #5 was summability and count-complexity. Approval is
> precinct-summable, and its count is the easiest and least
> computation-intensive, among voting-systems.
>
> Michael Ossipoff
>
>
>
>
>
>
>
>
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
>
>
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