[EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.
C.Benham
cbenham at adam.com.au
Tue Sep 13 06:17:32 PDT 2016
And I took " the max amount of upvotes" to refer to the maximum number
of up-votes received by any candidate.
Chris Benham
On 9/13/2016 10:31 PM, Jameson Quinn wrote:
> Chris is correct. "by most" = "by a majority". Maximum is "*/the/* most".
>
> Perhaps I should avoid that word, but I was trying to use small words,
> as in Randall Munroe's "Thing Explainer".
>
> 2016-09-13 6:28 GMT-04:00 C.Benham <cbenham at adam.com.au
> <mailto:cbenham at adam.com.au>>:
>
> Kevin,
>
> I take "downvoted by most" to mean down-voted by most of the
> voters, meaning down-voted on more than half the ballots.
>
> Your interpretation would be "the most downvoted".
>
> Chris Benham
>
>
>
> On 9/13/2016 2:56 PM, Kevin Venzke wrote:
>> Hi Jameson,
>>
>> "Downvoted by most" means the candidate with the single greatest
>> number of downvotes? This could be the (voted, unique) majority
>> favorite couldn't it?
>>
>> How does this violate "irrelevant ballots"? I must be
>> misunderstanding it. Does "max amount of upvotes" mean 100% of
>> the voters, or just the greatest number of upvotes that occurs?
>>
>> I do like antiplurality mechanisms.
>>
>> Kevin
>>
>>
>> ------------------------------------------------------------------------
>> *De :* Jameson Quinn <jameson.quinn at gmail.com>
>> <mailto:jameson.quinn at gmail.com>
>> *À :* Kevin Venzke <stepjak at yahoo.fr> <mailto:stepjak at yahoo.fr>;
>> electionsciencefoundation <electionscience at googlegroups.com>
>> <mailto:electionscience at googlegroups.com>
>> *Cc :* EM <election-methods at lists.electorama.com>
>> <mailto:election-methods at lists.electorama.com>
>> *Envoyé le :* Lundi 12 septembre 2016 20h37
>> *Objet :* Re: [EM] Fwd: Fwd: U/P voting: new name for simple
>> 3-level method.
>>
>> Here's a new proposed variant of U/P with a simple default:
>>
>> Voters may rate each candidate as "unacceptable" (downvote),
>> "preferred" (upvote), or "acceptable" (neither). Default is neither.
>>
>> Any candidate downvoted by most, or with fewer than half the max
>> amount of upvotes, is disqualified, unless that would disqualify
>> everyone. The winner is the remaining candidate with the most
>> upvotes.
>>
>> The "fewer than half the max" rule prevents dark-horse winners,
>> without resorting to strange defaults. It has no effect on a
>> two-way chicken dilemma. Though in theory it could affect an
>> evenly-balanced three-way chicken dilemma (in a four-way race), I
>> think there's a negligible chance that such a scenario would be
>> so balanced.
>>
>> I know that Chris doesn't like this method's violation of
>> "irrelevant ballots". Myself, I think that no voters are
>> irrelevant; even if they don't express an opinion between the two
>> frontrunners, they may have one. (True, they may not; but that's
>> not the first assumption I'd make.)
>>
>> 2016-09-12 20:22 GMT-04:00 Kevin Venzke <stepjak at yahoo.fr
>> <mailto:stepjak at yahoo.fr>>:
>>
>> Hi Jameson,
>>
>> I think it is a positive thing that the MTA B/C majority
>> coalition can give their sincere preferences (!), while using
>> the strategy they're expected to use (i.e. middle slot as
>> tiebreaker given multiple majorities), without risk of this
>> strategy backfiring. (Voters can accidentally elect the less
>> preferred of B or C, but that is the inescapable chicken
>> dilemma, I would say.)
>>
>> I have some sympathy for your claim that C should not be able
>> to win with few top ratings. But that sympathy is not tied to
>> Borda counts, it is based on wanting to reduce the truncation
>> incentive for the B voters. This, U/P does not really do,
>> because the B>C voters would be taking a large risk that they
>> are helping to put C (alone) over the threshold of majority
>> approval.
>>
>> So I don't think either of these ballot sets is likely under
>> U/P, and it sounds like you agree with that and think it is
>> good (because it deters a pathological ballot set)? Do you
>> have a stance (or at least, see use in determining a stance)
>> on how U/P voters in these scenarios should be voting?
>>
>> Kevin
>>
>>
>> ------------------------------------------------------------------------
>> *De :* Jameson Quinn <jameson.quinn at gmail.com
>> <mailto:jameson.quinn at gmail.com>>
>> *À :* EM <election-methods at lists. electorama.com
>> <mailto:election-methods at lists.electorama.com>>
>> *Envoyé le :* Dimanche 11 septembre 2016 1h51
>> *Objet :* [EM] Fwd: Fwd: U/P voting: new name for simple
>> 3-level method.
>>
>>
>>
>> 2016-09-10 21:26 GMT-04:00 C.Benham <cbenham at adam.com.au
>> <mailto:cbenham at adam.com.au>>:
>>
>> On 9/11/2016 5:02 AM, Kevin Venzke wrote:
>>
>> 43: A
>> 24: B>C
>> 23: C>B
>> 10: D
>>
>> Under MTA the B and C voters are being completely
>> reasonable: They hope for majority approval but can
>> still hope for a win if they
>> don't get it.
>>
>> Strategy is less likely to produce these ballots
>> under U/P because the B and C voters are taking a
>> gamble. To get a similar outcome
>> they have to vote B=C. Anyone who doesn't is
>> functionally defecting!
>>
>>
>> C: A very good example! Assuming MTA and MCA use Top
>> Ratings scores to break Approval ties, they both elect
>> the Condorcet winner B.
>>
>>
>> But both could be shifted to C with a single C-only ballot,
>> even if the B:C ratio were 46:1 instead of 24:23.
>>
>>
>> U/P's under-use of the middle ratings slot means that it
>> relies more on its "majority disqualification" mechanism
>> which seems to make it more
>> vulnerable to irrelevant ballots, as in the example.
>>
>> Under U/P, without the irrelevant D ballots, A and D are
>> disqualified and B is the glorious winner. With them, B
>> and C and D are disqualified and (without needing
>> any others to be disqualified) A wins.
>>
>> This causes me to reject U/P as clearly worse than MTA
>> and MCA. Of the three I (again) rate MTA as the least bad.
>>
>>
>> I think MTA is pretty darn good. I still prefer U/P.
>>
>> I think that scenarios like the above are fundamentally
>> pathological; any possible winner has only minority approval,
>> so that even assuming all ballots are semi-honest, any of
>> them could be a true Condorcet loser. Thus, I believe that
>> it's more important for a system to try to avoid scenarios
>> like the above, than to try to find a perfect winner in such
>> a scenario. In fact, in the related scenario:
>>
>>
>> 43: A
>> 40: B>C
>> 6: C>B
>> 1: C
>> 10: D
>>
>> ... I think that a case can be made for either A or B. After
>> all, they'd be tied if we try to approximate Score by using
>> truncatable Borda here. But no serious case can be made for C
>> or D, even though C wins MTA and MCA.
>>
>> Anyway, I think U/P does a better job trying to discourage
>> the kind of strategy that would lead to a scenario like the
>> above. And part of that is the default rule which Chris has
>> criticized.
>>
>> One possible alternative default rule: ballots alternate
>> between defaulting to "acceptable" and to "unacceptable".
>> Each ballot clearly states which default it uses, and there
>> is a place on the ballot to globally change that default. (I
>> doubt Chris will like this idea, but it is at least
>> straightforward, explicit, and easy to describe.)
>>
>>
>> Chris Benham
>>
>>
>>
>>
>>
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