Jonathan makes an important point. The term "spoiler" means a minor candidate with a small percentage of the vote, who changes which of the other candidates wins by running. But Kathy and some others wish to expand the definition to include a front-runner. (Note that these IRV opponents refer to the top plurality vote-getter who narrowly lost the runoff in Burlington, Kurt Wright, as a "spoiler" who prevented the candidate in third place from winning. This is a dynamic worthy of analysis, but the word "spoiler" is never used by the media or political scientists when describing the plurality leader.
Terry Bouricius ----- Original Message ----- From: "Jonathan Lundell" <[email protected]> To: "Juho" <[email protected]> Cc: "EM Methods" <[email protected]> Sent: Thursday, January 21, 2010 10:33 AM Subject: Re: [EM] I need an example of Condorcet method being subjected tothe spoiler effect if any On Jan 21, 2010, at 1:03 AM, Juho wrote: > What is good in all the common Condorcet methods is that their > vulnerabilities to strategies (and their differences in general) may > very well be so small in typical real elections (large, public, with > independent voter decision making, with changing opinions and less than > perfect poll information) that strategic voting will not be a problem. > Also their differences with sincere votes (e.g. spoiler related > problems) are quite small in real life elections. > > Here's one simple spoiler related example as a response to Kathy Dopp's > request. > > 35: A>B>C > 33: B>C>A > 32: C>A>B > > I this example there are three candidates in a top level cycle. If any > of the candidates would not run that would mean that there is a > Condorcet winner, and that winner would be different in each case. Let's > say that the method we use will pick A as the winner. If B would not run > then the votes would be 35: A>C, 33: C>A, 32: C>A and C would win. B is > thus a spoiler from C's point of view. > > I note however that these spoiler cases in Condorcet are not as common > as in many of the other methods. In practice it may be that there is no > need to worry about these cases. Maybe Kathy Dopp's comparisons will > reveal something about how problematic the spoiler effect is or is not > in Condorcet. Not also that in the example above B was not a minor party > candidate (often term spoiler refers to minor candidates) but a pretty > strong candidate. In that case it might be a good starting point to define "spoiler", so we know what we've found when we find it. What's an example of an IRV spoiler who's not a "pretty strong candidate"? ---- Election-Methods mailing list - see http://electorama.com/em for list info ---- Election-Methods mailing list - see http://electorama.com/em for list info
