[EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.

Tue Sep 13 06:28:49 PDT 2016

Again, correct.

2016-09-13 9:17 GMT-04:00 C.Benham <cbenham at adam.com.au>:

> 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>:
>
>> 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> <jameson.quinn at gmail.com>
>> *À :* Kevin Venzke <stepjak at yahoo.fr> <stepjak at yahoo.fr>;
>> electionsciencefoundation <electionscience at googlegroups.com>
>> <electionscience at googlegroups.com>
>> *Cc :* EM <election-methods at lists.electorama.com>
>> <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>:
>>
>> 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>
>> *À :* EM <election-methods at lists. electorama.com
>> <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>:
>>
>> 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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