IEVS 2.56 now includes 11 different utility generators, based either on random normal numbers, or on positions in an I-dimensional issue space for I=1,2,3,4,5, and utilities based on either a function of distance, or dot product, between candidate and voter issue-stance-vectors.
It also includes over 50 different voting methods. Also it includes adjustable voter "ignorance" and adjustable voter strategy-vs-honesty mix. Unfortunately all that means the damn thing now takes about a week to run and produces about 100 Megabytes of output. I need to do something about that. The results so far [PRELIMINARY] are that range voting is always at the top of the heap - meaning its Bayesian regret is the least of all voting methods (of those programmed, and up to noise comparable to one standard statistical error) EXCEPT for the following: * Range+top2runoff (and sometimes approval with top-2-runoff, and perhaps sometimes HeitzigDFC, but those both appear to be dominated by range+top2runoff and HeitzigDFC appears to be dominated by Approval+top2runoff) beat plain range's Bayesian Regret in circumstances with enough strategic voters in the mix. Note the top2runoff part is honest voting even for strategic voters. The crossover point is approximately at a 50-50 honest-strategic voter mix. * Top median Rating and maybe MCA are occasionally up there with the big boys, although usually not and never clearly surpass them. MCA seems to dominate approval, although it is often exactly the same (and is more complicated). * There may be some future addenda to this list as IEVS grinds further. The really bad voting methods at the bottom of the heap (usually near the bottom and sometimes with over 3 times as bad Bayesian Regret as the best method) include HeitzigLFC, RandomWinner, Hay, RandomBallot, ContinCumul, LoMedianRank, AntiPlurality, Plurality, VenzkeDisqPlur, Bucklin, BaseballMVP, Coombs, Dabagh, Nauru, and Top3IRV (listed in a roughly improving-quality direction). If there are enough strategic voters, then Range and Range+top2runoff both give a higher probability than everything else (including "Condorcet methods") of selecting a (true-utility-based) Condorcet winner. The crossover point is approximately at 70-30 honest-strategic voter mix. Mike Ossipoff has pointed out that the theorem in http://rangevoting.org/AppCW.html which explains how (a certain plausible kind of) strategic range voters can generate a Condorcet winner with 100% probability, is really part of a larger claim that EVERY voting method, with informed strategic voters, will generate a Condorcet winner with 100% probability. (The AppCW file now includes a note to that effect. This may have been pointed out by Niemi and/or Riker in the 1970s.) However, Ossipoff's claim is not quite true. It is true for a large class of (but not all) voting methods, and for certain kinds of strategic voter behavior within those methods (how plausible those behaviors then are, is subject to debate), yes. Anyhow, the IEVS simulation is finding range and range+top2runoff are ESPECIALLY good at generating honest-condorcet-winners. The other methods, contrary to the Ossipoffian all-inclusive view, are not able to equal range and range+top2runoff in that respect. Future plans (in the rough order I plan to do them): 1* I want to build a "reality based utility generator" based on Tideman's dataset of 87 real world elections (plus some more elections). Your contributions? 2* Add more voting methods. Your suggestions? 3* Add more voter-strategies. Your suggestions? 4* Add stuff to permit rank-order WITH EQUALITIES PERMITTED ballots. That will also interact with 2 and 3, unfortunately. If you want to help: the more work you do, the more help it'll be and the more likely I'll incorporate it. I.e. providing an election in a NICE FORMAT is a hell of a lot better than just pointing me to some election data somewhere in the format from hell. (Burlington and Ireland = hell.) Nice formats include something like the format Debian uses for their elections (e.g. see http://www.debian.org/vote/2005/leader2005_tally.txt ), or Tideman's format (http://rangevoting.org/TidemanData.html). Debian format permits equal rankings, Tideman does not. Providing actual or pseudo-code for a voting method is a hell of a lot better than just babbling, and the more detailed the pseudo-code, the better. The present IEVS code is available as always at http://rangevoting.org/IEVS/IEVS.c Warren D Smith http://rangevoting.org warren.wds AT gmail.com ---- election-methods mailing list - see http://electorama.com/em for list info
