[EM] A distance based method

[Jameson Quinn]

This system seems explicitly designed to elect a centrist. In their
experimental paper<https://sites.google.com/site/ridalaraki/xfiles/BalinskiLarakiExperiEvid%28LastVersion%29.pdf?attredirects=0>on
Majority Judgment, system inventors Badinski and Laraki run a
simulation
to see how often different systems elect a centrist. Most systems they test
either elect the centrist almost always (ie, condorcet systems) or almost
never (plurality, IRV, runoffs), but their MJ system does about half the
time. They argue that this "lack of bias" either towards or away from
centrists is best, because a system which is too skewed to the middle or to
the extremes will distort the political dialogue in corresponding ways.
Though I think their simulation is just a rudimentary first step, I find
their normative argument convincing; and so I don't really like this
"distance" method.

JQ

2011/7/10 <fsimmons at pcc.edu>

> First find a clone consistent way of defining distance between candidates.
>
> Then while two or more candidates remain
>  of the two with the greatest distance from each other
>  eliminate the one with the greatest pairwise defeat
> EndWhile.
>
> Various variants are possble.  For example, you could count defeats only
> from the remaining
> candidates.  Also there are various possible measures of defeat strength.
>  In that regard, if you say that
> any defeat by covering is stronger than every non-covering defeat, then the
> method will always elect a
> covered candidate.
>
> To get a distance estimate in a large election you could just ask each
> voter to list the pair of candidates
> that seem the most different on the issue or combination of issues of most
> concern (to that voter).  The
> pair submitted by the greatest number of voters would be the first pair
> considered, etc.
>
> What potential for manipulation does this direct approach introduce?
>
> Perhaps voters would try to pit their favorites' rivals against each other.
>  Would that be insincere?  Not if
> they consider their favorite to have a reasonable middle of the road
> position, while viewing the rivals as
> being at opposite unreasonable extremes.
>
> What indirect measure of distance could be used?
>
> If we count the number of ballots on which candidates X and Y are ranked at
> opposite extremes (top
> rank for one versus unranked for the other), the monotonicity of the method
> would probably be
> destroyed.  Is there a more subtle way of inferring the distance that
> wouldn't destroy the monotonicity?
>
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