Response to Warren... inserted below each of his points (marked by ***) Terry Bouricius
----- Original Message ----- From: "Warren Smith" <[email protected]> To: "election-methods" <[email protected]> Sent: Sunday, November 08, 2009 1:00 PM Subject: [EM] (no subject) >Terry Bouricius: I'm not sure if it is quite at the layman level, but Prof. Nicloaus Tideman's recent book "Collective Decisions and Voting" has an analysis of vulnerability to strategic manipulation of virtually every single-winner voting method that has ever been proposed and concludes that Range Voting along with Borda and four other methods "have defects that are so serious as to disqualify them from consideration." (page 238). Range Voting advocates on this list dispute his definition of "resistance to strategy." >A somewhat more accessible (and available online for free) analysis of strategic vulnerability of various methods is in this doctoral paper by James Green-Armytage ("Strategic voting and Strategic Nomination: Comparing seven election methods"). He found that Range and Approval were just about the worst in terms of manipulability. http://econ.ucsb.edu/graduate/PhDResearch/electionstrategy10b.pdf >REPLY BY WDS: 1.Tideman's book and the flaws in its (poor) notion of "resistance to strategy" are discussed here: http://rangevoting.org/TidemanRev.html *** 1. Tideman is quite careful and methodical in his analysis of resistance to strategy using real world election data as a basis for analysis. I agree, however, that his definition only covers a specific slice of strategy possibilities that his data allowed him to analyze, and he made no attempt to evaluate other kinds of possible startegy that Warren Smith and some others focus on. This does not mean Tideman's analysis is flawed, though it may be classified as incomplete. >2. Bouricius forgot to mention, same way he usually forgets to mention, that Tideman also found IRV to be "unsupportable." *** 2. Warren Smith is wrong. He either hasn't read Tideman or is intentionally miss-representing Tideman here. On page 238 Tideman has a chart with five categories of summarizing his analysis of mehtods... First is "Not supportable" whcih includes Borda, Range, Dodgson, Copeland, Coombs and Est. centrality. The next category is "Arguably inferior to maxmin" which includes Condorcet, Simp. Dodgson, Nanson, Bucklin, Black, Young, and Wt. Condorcet. The third categroy is "Supportable if ranking is infeasible" which includes Plurality, Approval, and Two-ballot majority. The fourth category is "Supportable if a matrix is uncalculable" whcih includes only Alternative vote [IRV] The last category is "Supportable if a matrix of majorities is calculable" which includes Maxmin, Ranked Pairs, Schulze, Alt. Scwartz and Alt. Smith. Warren is assuming that a matrix is always "calculable" and thus the supportable category that includes only IRV is in fact null. However, that is not what Tideman is arguing (or why would he create the category if it was always empty)? Elsewhere he discusses the practical limitations of voting methods used for public elections including ease of voter acceptance and argues that a hypothetical improvement of a system that requires complexities such as matrices may be impractical in large scale elections. He writes on page 240 "If it is feasible to require voters to rank options, then much more sophisticated processing is possible. However, it is conceivable that it would be feasible to require voters to rank options but not feasible to require vote-processors to produce a matrix of majorities. In this event the Alternative vote is supportable." >3.Armytage's ideas & related ones are discussed in puzzle #112 here: http://rangevoting.org/PuzzlePage.html (I actually managed to prove a number of things Armytage could not, for example.) However Bayesian Regret is the right yardstick and Armytage's (while interesting) the wrong one. ***3. Warren Smith's conviction that Bayesian Regret is the gold standard for evaluating voting methods is not universally, nor even very widely held. It is a unique philosophical view held by those who subscribe to the Utilitarian philosphy, and is at least arguable. Many (most) people believe that when electing a single seat, the will of the majority should win out over the minority. This is necessarily rejected by the believers in Bayesian Regret and advocates of Range voting. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step) and math.temple.edu/~wds/homepage/works.html ---- Election-Methods mailing list - see http://electorama.com/em for list info ---- Election-Methods mailing list - see http://electorama.com/em for list info
