2009/2/17 Kristofer Munsterhjelm <[email protected]> > Diego Santos wrote: > >> 2009/2/15 Dan Bishop <[email protected] <mailto:[email protected] >> >> >> >> >> STV-CLE just happens to work the best when the political spectrum is >> one-dimensional: Candidates are eliminated at the ends of the >> spectrum until someone has a quota, and the process continues until >> candidates are neatly spaced a quota apart. >> >> But with multiple dimensions, the CLs' votes get split among >> multiple candidates, so you have to eliminate more candidates until >> someone meets quota. This creates a much stronger centrist bias >> than the 1-dimensional case. >> >> >> The flaw in STV-CLE I see is that the candidate elimination heuristics is >> based in a majoritarian criterion in a PR method. I think that a good >> heuristic to eliminate a candidate should be based a PR quota, like >> Newland-Britton. Some months ago I desgined the "Bucklin elimination STV" (I >> don't have a definite name for it). When no candidate reaches a quota, then >> later preferences are added until some candidadate reaches the quota. But, >> instead of this candidate is considered elected, the candidate with the >> least sum is eliminated. Some examples with this method has generated good >> outcomes. >> > > What's so tricky about PR is that in some respects it's majoritarian and in > others not. For instance, in a situation where you have candidates A1..An > and a Condorcet type method elects A1, then if duplicate all ballots, only > changing A1 to B1, A2 to B2, etc, so that one "faction" of half the > electorate votes as before, and the other faction votes the same way but > with B* instead of A*, then A1 and B1 should win. That's both > non-majoritarian (recognizing the factions) and majoritarian (within the > factions). > > Your method may be nonmonotonic, since many elimination methods are.
Yes, this method probably violates monotonicity. > Have you tried the other Bucklin generalization, where one elects the > candidate that exceeds the quota and then does a reweighting? I suppose > elimination gets you out of having to reweight. I tried a method that after I discovered identical to Benham's Generalized Bucklin PR 2.3. > > > Perhaps that idea could be used for my "weighted positional STV" method > where I never got reweighting to work properly. > Maybe monotonicity failure can be avoided if instead of eliminate some candidate, just collapse the ballots where this candidate is in first with its next preferences. -- ________________________________ Diego Renato dos Santos Mestrando em Ciência da Computação COPIN - UFCG
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