[EM] Interpreting Balinski's MJ words

[Kevin Venzke]

Hi Kristofer,
I realize you are only interpreting B&L, so I don't mean to shoot the messenger.

      De : Kristofer Munsterhjelm <km_elmet at t-online.de>
 À : steve bosworth <stevebosworth at hotmail.com>; "election-methods at lists.electorama.com" <election-methods at lists.electorama.com> 
 Envoyé le : Mercredi 4 janvier 2017 6h45
 Objet : Re: [EM] Interpreting Balinski's MJ words
   
>> /strategy-proof-in-grading/.  A group of voters who share the same
>> beliefs (e.g.
>> they belong to the same political party) has the same optimal strategy,
>> namely, to
>> give to the candidates the grades it believes they merit. 
You clarified your original response to this in saying:
>You're right that the voters can only very rarely change the outcome.
>But the point beyond this observation is, as I said, that even when they
>can, it's detrimental for them to do so.
>
>That is assuming they're strategizing in grades, i.e. want Royal to get
>a Good rather than Royal to win.

Do you find it easy to imagine a scenario where a group of like-minded voters has this as a strategic goal? At the very least, this description of the goal would be quite abbreviated from what the actual thought must be.There's no benefit in trying to give Royal a "Good" median rating if no scenario is envisioned where Royal could win with this rating. 
>> One means by which it [MJ] resists [manipulation] is easy to explain.
>> Take the example of Bayrou with a /Good/+ and Royal with a /Good/− (see
>> table 1.4); their respective
>> majority-gauges are
>>   ...
>> But the majority judgment is /partially
>> strategy-proof-in-/
>> /ranking/: those voters who can [might marginally be able to] lower
>> Bayrou’s majority-gauge cannot [significantly] raise
>> Royal’s, and those who can [might marginally be able to] raise Royal’s
>> majority-gauge cannot [significantly] lower Bayrou’s.

>Again, the point here isn't directly that the outcome doesn't often
>change. (That the outcome doesn't often change is beneficial for other
>reasons, some of which are related to strategy.)
>
>The main point is instead:
>
>Suppose some voter ranks Royal above Bayrou, like this:
>
>Excellent | Good | Fair  | Poor | Reject
>..........|.Royal|.Bayrou.|......|.......
>
>Then if the voter wants to make Royal rather than Bayrou win, she can
>push Royal up or Bayrou down.
>
>But she can only push Bayrou down from where Bayrou is ranked on her
>honest ballot, and can only push Royal up from where Royal is ranked on
>her honest ballot.
>
>And in effect, this makes only half the ballot available to do either.
>If the voter has ranked Royal highly, she can push Bayrou down but can't
>move Royal even higher. On the other hand, if the voter has ranked Royal
>closer to the Reject end, she can push Royal higher (up to Excellent),
>but can't push Bayrou very far down.
>
>So a voter can only either exaggerate Royal (if she graded Royal low on
>the original ballot) or exaggerate Bayrou (if she graded Bayrou high),
>but not both at the same time.
>
>The example voter above has graded Royal pretty high and so can only
>exaggerate by one step - by moving Royal from Good to Excellent. On the
>other hand, she can move Bayrou all the way from Fair to Reject.
This sounds like they are saying that it's a noteworthy quality of MJ that an expressed preference strength can'texceed the range of the ballot...? What method could we even compare?
Kevin
   
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