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

Tue Sep 13 20:39:49 PDT 2016

Ok. It took me a little while to conclude that "most" was intended to be the end of that noun phrase. I saw that it had to be, but also wondered whether there was a missing word or something.
This method is sort of like a ratings version of my disqualified plurality method (on a "vote for and against" ballot), which also disqualifies only if there's a full majority. But my method can only elect either the first- or second-place candidate (by "for" votes).
I imagine most voters wouldn't use the middle slot in this method.
Kevin

      De : Jameson Quinn <jameson.quinn at gmail.com>
 À : C.Benham <cbenham at adam.com.au> 
Cc : Kevin Venzke <stepjak at yahoo.fr>; EM <election-methods at lists.electorama.com>
 Envoyé le : Mardi 13 septembre 2016 8h01
 Objet : Re: [EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.

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>
 À : Kevin Venzke <stepjak at yahoo.fr>; electionsciencefoundation <electionscience at googlegroups. com> 
 Cc : EM <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> 
 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 "majoritydisqualification" 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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