[Election-Methods] MCA's IIB problem fixed

[Chris Benham]

Chris Benham wrote:

> And  I  think there are better 3-slot  FBC-complying,  LNHelp failing 
> methods that use
> MPO information combined with ratings information (than my suggested 
> modified MCA).

Kevin,
Or (for the record) maybe not clearly better.  Can you suggest a name 
for  my  "IIB fixed"
version of  MCA?  Maybe something like  "MCA-MMPO"?

> One possibility:  "If  any candidates have a top-ratings score not 
> smaller than their  MPO
> score, disqualify the other candidates.  Elect the undisqualified 
> candidate with the highest
> Approval-minus-MPO score".

For example this may not meet  Possible Approval Winner (PAW).


Chris Benham

>
> Kevin,
> I just realised that my suggested IIB-fix of  MCA  does cost a 
> criterion compliance:
> Later-no-Help.  Adding  middle-ratings can help top-rated candidates 
> by maybe
> increasing the Max Pairwise Opposition of  their rivals.
>
> I consider having LNHelp and  LNHarm in  (at least probabilistic) 
> balance to be more
> desirable than either by itself,  so  I  don't mind losing  MCA's  
> LNHelp  (since it badly
> fails LNHarm).  But  I have to withdraw my suggestion that  MCA 
> doesn't have (for a
> 3-slot method) a maximal set of properties.
>
> And  I  think there are better 3-slot  FBC-complying,  LNHelp failing 
> methods that use
> MPO information combined with ratings information (than my suggested 
> modified MCA).
>
> One possibility:  "If  any candidates have a top-ratings score not 
> smaller than their  MPO
> score, disqualify the other candidates.  Elect the undisqualified 
> candidate with the highest
> Approval minus MPO score".
>
>
> Chris  Benham
>
>
>
>
> Kevin Venzke wrote:
>
>>Chris,
>>
>>--- Kevin Venzke <KVenzke at markjamesassociates.com> a écrit :
>>  
>>
>>>Kevin,
>>>
>>>Kevin Venzke wrote:
>>>
>>>As far as my strategy simulation is concerned, this rule change raises
>>>the
>>>question of how voters should evaluate the possibility that they elevate
>>>a
>>>candidate to the top spot on first preferences only to see him lose due
>>>to
>>>pairwise opposition.
>>>
>>>    
>>>
>>Chris replies:
>>  
>>
>>>I don't fully understand this point.  Any candidate who would win in the
>>>first round of regular  MCA would 
>>>also win in the first round of  my suggested version, and in both the FPW
>>> can win in the second round.
>>>The only difference is that my version is more likely to have a
>>>first-round winner, which I suppose in the
>>>FBC-complying 3-slot ballot version might be a bit self-defeating.  In
>>>your  FPP-approval ballot version
>>>I don't see how it greatly complicates the strategy.
>>>    
>>>
>>
>>Currently the value of a first-preference vote for A is estimated as the
>>likelihood that A can achieve majority times the likelihood that no
>>candidate will achieve majority (e.g. if a majority is guaranteed then no
>>vote is of value) times the difference between A's utility and your
>>expectation should the election be resolved on approval.
>>
>>With your rule you no longer simply break ties between one candidate's
>>majority and "no majority"; you have to compare against each other
>>candidate FPP-style. And you can't simply compare the candidate's utility
>>to the approval expectation, because the candidate could lose despite
>>coming in first.
>>
>>If I were implementing this method I would probably have voters keep track
>>of their expectation when each candidate is the TRW but has too high
>>pairwise opposition. This kind of approach so far has produced a lot of
>>intelligent behavior. It has a couple of downsides though: 1. Voters can't
>>predict the value of situations which weren't observed to occur in the
>>polls, and thus won't try to create them, and 2. There seem to be a number
>>of "cum hoc ergo propter hoc" mistakes where voters vote for situations
>>that have coincided with outcomes they liked, but which didn't necessarily
>>cause them.
>>
>>Kevin Venzke
>>
>>
>>      _____________________________________________________________________________ 
>>Ne gardez plus qu'une seule adresse mail ! Copiez vos mails vers Yahoo! Mail http://mail.yahoo.fr
>>
>>----
>>Election-Methods mailing list - see http://electorama.com/em for list info
>>
>>
>>  
>>
>------------------------------------------------------------------------
>
>----
>Election-Methods mailing list - see http://electorama.com/em for list info
>  
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20080201/1743d051/attachment-0003.htm>