MAS is Bucklin (thanks Nevin)

[Jameson Quinn]

As Nevin Brackett-Rozinsky recently pointed out, the only difference between MAS and a rated Bucklin (that is, top median, with tiebreaker) system is that MAS doesn't explicitly state that a candidate with a majority of top-votes (2's) cannot be beaten by one without such a majority. Of course, in the real world, that rule would be highly unlikely to ever have any impact. If one candidate gets over 50% top-ratings, there is very little chance that there's another candidate who's even close to them in total score, let alone one who beats them.

Still, I think Nevin's is a useful insight, because it helps tie MAS to the history of Bucklin as used in the Progressive-era US. One of the first criticisms MAS will get is that it's a recent innovation, and it needs a "track record". Saying that "it's just a form of Bucklin, and thus closely related to voting systems that were used in over a dozen US cities" is a decent comeback. 

Over at the MAS electowiki page I've fixed things up to show this link.

[Warren D Smith]

oh, well, if MAS is Bucklin, then I think it was really invented before;
Chris Benham a long time ago
(15-25 years?) invented a 3-level system he called MCA (majority
choice approval),
which as somebody (Jameson himself?) pointed out is actually Bucklin
in 3-candidate elections, and also related to Balinski-Laraki
"majority judgment".

MCA was a strong performer in my Bayesian regret testing.

It wasn't obvious to me exactly why MCA did so well and it led to me
wondering if there
is something specially good about "3" levels in "majority judgment."
Anyhow, it seems to me if one wanted to get serious about this there are various
ways to parameterize it and then you could try to optimize the parameters to
minimize BR in various models.



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Warren D. Smith
http://RangeVoting.org <-- add your endorsement (by clicking
"endorse" as 1st step)

[Jameson Quinn]

Yes, I'm pretty sure that it's been proposed before. But it's not the same as MCA, because the tiebreaker is different. (Better against the chicken dilemma, yet still not too bad in terms of center squeeze.)

In terms of VSE (aka BR), I'm pretty sure you could cook the voter model to give lots of nearly-balanced chicken dilemmas, and trip up "honest" (normalized) score, thus making MAS actually come out better than score. If you don't put your finger on the scales, I think this would happen occasionally, but also score would come out ahead occasionally, and so I'm not sure which would win overall. Probably score, but not by a huge margin. 

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