[EM] Trying to have CD, protect strong top-set, and protect middle candidates too

[Michael Ossipoff]

Alright, thanks!  That answers my question about how one of your
Approval/Pairwise proposals (Pairwise-Sorted Approval)  relate to these
goals, and it means that, there's a good,brief and natural definition
that's equivalent to Smith//Approval.

That's briefly-defined enough to be in the list of methods that should be
offered to the public and to the initiative proposal committee when a
voting-system reform is being considered.

Your other Approval/Pairwise method that I remember, the Approval
Cover-Ladder method, is probably too complicated though.

I'm looking at some of the old proposals, including MDDA, MDDTR, MAMPO,
MMD-Bucklin, etc, that might do well by the standards that I spoke of.

I personally prefer MDDTR to MDDA, if people only use below-top ranking
when absolutely necessary in a chicken-dilemma situation. ...because I'd
rather have CD than routine use of middle ranking.

But, especially if the method wouldn't always be used in that way, MDDA
would be a lot safer from an embarrassing & bad result due to its poor
protection from burial.

Michael Ossipoff



On Wed, Nov 16, 2016 at 5:30 PM, Forest Simmons <fsimmons at pcc.edu> wrote:

> Here's a simple method that is essentially Smith//Approval without having
> to mention the Smith set:
>
> List the candidates in order of approval, highest to lowest, top to
> bottom.  While any candidate pairwise beats an adjacent candidate higher in
> the list, switch places of the two lowest out of order adjacent members.
>
> When there remains no out of order adjacent pair, elect the candidate at
> the top of the list.
>
> Note that the winner will automatically be a member of the top cycle, and
> if it is a cycle of three, it will be the most approved member of the cycle.
>
> Also notice that it yields an unambiguous social order, and that there can
> be no second place complaint.
>
> On Tue, Nov 15, 2016 at 5:19 PM, Michael Ossipoff <email9648742 at gmail.com>
> wrote:
>
>> When I started my current EM participation, I was saying that 3-Slot ICT
>> was my favorite method.
>>
>> That doesn't conflict with saying that I consider Approval the best,
>> because I regard 3-Slot ICT, or unlimited-rankings ICT (when used
>> approval-like) as an Approval version without chicken-dilemma.
>>
>> Later I realized that MDDTR is better than ICT, because it gives better
>> protection to middle candidates.
>>
>> I measure that protection by how well they'd be protected if they were
>> CWs.  ...what it would take to protect their win, and how well it's
>> protected.
>>
>> I define "middle candidates" as candidates you rank or rate below top and
>> above bottom.
>>
>> ICT gives no protection to middle candidates, against burial, or even
>> against innocent, non-strategic truncation--the two things that threaten a
>> CWs in pairwise-c0unt methods.
>>
>> MDDTR gives full truncation-proofness to middle candidates, but (contrary
>> to what I earlier believed), its protection of middle candidates against
>> burial can only be called "shabby".
>>
>> By the way, I no longer think that ICT or MDDTR needs to be 3-slot.
>> 3-Slot would be fine with me, because I believe that ICT or MDDTR should be
>> used as Approval, and that middle rating or ranking should only be used
>> when seriously needed to deter chicken-dilemma defection. When middle is
>> used in an unlimited-ranking MDDTR or ICT, it should probably consist of
>> 2nd-place ranking, if you want to give the demoted candidates the best
>> protection.   ...but maybe you'd rather rank them with respect to
>> eachother, at different middle levels, as I probably sometimes would.
>>
>> But, as I've been saying, activists & organizations seem to like
>> rankings, and some people--overcompromisers & rival parties--might very
>> well need rankings to soften their voting errors.
>>
>> And it seems to me that there's no particular reason not to rank, in
>> order of preference, your middle candidates, if some of them are better
>> than others, or if the voters of some of them are less trustworthy than
>> others.
>>
>> So, that's if you want CD, in addition to FBC, and good protection for
>> middle candidates
>>
>> Even if you're using the method as Approval, you still want your demoted
>> candidate(s) to be well protected. Just because you don't trust hir voters
>> doesn't mean you want to throw her to the hounds and thereby lower Pt, the
>> probability of electing from your strong top-set.
>>
>> Anyway, so far, this is all referring to CD methods.
>>
>> Of those, I like MDDTR best. As a rank method, it (as i said) gives only
>> shabby burial-protection to a middle candidate. But evidently (please tell
>> me it isn't so) you can't have FBC, CD, and good protection of middle
>> candidates.
>>
>> I consider CD more important to how well protected middle candidates are.
>> Yes, FBC + CD give poor protection to middle candidates, and that lessens
>> the value of their CD. But non-CD methods don't have CD at all, and that's
>> worse.
>>
>> So I prefer MDDTR to methods that give better protection to middle
>> candidates, but don't have CD.
>>
>> So, where I used to say that my favorite method is 3-Slot ICT, now I say
>> that my favorite method is MDDTR. Preferably with unlimited rankings.
>> (Though one could use only the 1st, 2nd, & bottom positions if one chose
>> to).   ...regardable as a chicken-dilemma-free version of Approval.
>>
>> ------------------------------------------------------------------
>>
>> Non-CD methods with better "middle-strategy" than CD methods:
>>
>> But, in an election, I'm just one voter, and so, how well-suited the
>> method is to me is less important, and won't affect the outcome as much, in
>> comparison to how well-suited the method is to lots of progressives.
>>
>> So, what if most progressives would rather have a method that's really
>> good as a rank method, a method that has good "middle strategy" (strategy
>> for protecting a middle candidate's win if s/he's CWs).
>>
>> That would be important if you knew that all or nearly all, or even most
>> of them were going to use the method purely as a rank method.
>>
>> Bucklin is the traditional FBC rankings-method.
>>
>> I distinguish 2 kinds of middle strategy merit:
>>
>> 1. How well the method protects top-ranked candidates against
>> middle-ranked candidates. I call that "Middle1"
>>
>> 2. How well the lmethod  protects a middle-ranked candidate against any
>> candidate you rank lower than hir. I call that "Middle2".
>>
>> So, how to get the best middle strategy, with the main goal still being
>> keeping a good probability, Pt, of electing from your strong top-set?
>>
>> MDDTR's middle1 seems better than that of Bucklin. In MDDTR, you're
>> voting to contribute to a majority for your top against your middle. In
>> Bucklin, you can protect top against middle by skipping some rating-levels
>> above the middle candidates. In that way, you can give the top candidates
>> time to receive the coalescing lower-choice votes that they'll get from the
>> preferrers of other candidates, before giving anything to the middle
>> candidates.
>>
>> That's a bit more work than just ranking in order of preference. It
>> requires you to judge where, and how far down in rankings, your top
>> candidates are going to receive lower-choice votes from.
>>
>> So I suggest that MDDTR does better at Middle1 than Bucklin does.
>>
>> But Bucklin does better at Middle2.
>>
>> In Bucklin, the CWs's win is protected by the people who pretty-much
>> agree with you, the people of your wing, merely not ranking down too far.
>>
>> MDDTR needs that too, but it isn't enough to give MDDTR more than shabby
>> protection.
>>
>> ...And Bucklin's Middle1, though not as convenient or easy as that of
>> MDDTR, isn't as questionable as MDDTR's Middle2.
>>
>> So, overall, I'd say that Bucklin's Middle Strategy is better than that
>> of MDDTR. So, for people who want to use the method purely as a
>> rank-method, Bucklin is better than MDDTR.
>>
>> Bucklin also has the advantage of use-precedent.  MDDT has the advantage
>> of precinct-summability,but I don't consider that essential.
>>
>> For voters using the method purely as a rank method, I'd prefer Bucklin
>> to MDDTR.
>>
>> Chicken dilemma won't happen all the time, probably won't happen often.
>> But middle-protection will always matter to people using it as a rank
>> method.
>>
>> But it seems to me that, once we give up CD (for voters who need good
>> middle strategly, because of their rank voting), then it might be possible
>> to do better than Bucklin.
>>
>> It seems to me that methods that use both Approval and pairwise-count can
>> do better than Bucklin, at middle protection.
>>
>> A lot of methods of that kind have been proposed, and I've ignored all of
>> them because they don't meet CD. But, as mentioned above, for some
>> electorates, middle strategy could be more important.
>>
>> It seems to me that MDDA (also evidently named MPOA) and Smith//Approval
>> are two methods that might be better than Bucklin at middle protection..
>>
>> Using Approval as the cycle-solution is a very powerful idea (if you're
>> willing to give up CD, for an electorate's needs). But most of you already
>> knew that, before I paid attention to it (...because I was only looking at
>> CD methods)..
>>
>> MDDA's & Smith//Approval's burial vulnerability doesn't matter much, when
>> the Approval winner wins the cycle. In fact, Smith//Approval's
>> truncation-vulnerability could even be regarded as an advantage, for when
>> your strong top-set doesn't include the CWs.
>>
>> MDDA & Smith//Approval look better to me than Bucklin.
>>
>> Simpler Middle1.
>>
>> Precinct-Summability is an added bonus.
>>
>> MDDA seems to have a briefer definition than either Bucklin or
>> Smith//Approval, and brief definition can be decisive.
>>
>> I know of Bucklin being rejected when MDDTR was accepted. MDDA would
>> almost surely have been accepted too.
>>
>> I don't  think Smith//Approval would go over well, with its need to
>> define the Smith set, which greatly lengthens the definition.
>>
>> For an electorate that need good Middle1 & Middle2 more than CD, MDDA
>> seems the winner so far.
>>
>> Smith//Approvsl of course meets Smith.  ...which of course means that it
>> fails FBC. But does it need FBC?
>>
>> It could be argued (but I don't know if it's true) that Smith//Approval
>> doesn't need FBC, because, though you don't have an efffective Approval
>> vote at the top, you still can vote Approval, with the approval-cutoff, or
>> by only ranking your strong top-set.
>>
>> So, though Compromise could become pair-beaten by Favorite because you
>> raise Favorite to top with Compromise, resulting in a cycle instead of a
>> CWv win for Favorite, the cycle will be judged by approvals, and you're
>> approved only your strong top-set.
>>
>> Of course, just because Favorite was almost the CWv doesn't necessarily
>> mean that s/he'll win the Approval count. But are you any worse off than
>> you'd have been with MDDA?
>>
>> Forest (but maybe others too) has proposed a number of methods that
>> combine pairwise-count and Approval. Do any of those beat MDDA &
>> Smith//Approval by the standards of protecting one's strong top-set, and
>> Middle1 & Middle2?
>>
>> in particular, do any of them do better than MDDA by those standards? Do
>> any do as well as MDDA by those standards and have as brief a defintion, or
>> nearly as brief a definition?
>>
>> In other words, are there methods that achieve those things better than
>> MDDA & Smith//Approval, or achieve them better than MDDA and have as brief
>> a definition?
>>
>> In fact, is there a method that meets FBC (or doesn't need it), meets CD,
>> and does as well by Middle1 & Middle2 as MDDA, Smith//Approval or Bucklin?
>>
>> Michael Ossipoff
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