Chris Benham wrote: > I'm happy with its performance in this old example: > > 101: A > 001: B>A > 101: C>B > > It easily elects A. Schulze (like the other Winning Votes "defeat dropper" methods) elects B. > > It meets my "No Zero-Information Strategy" criterion, which means that the voter with no idea how others will vote does best to simply rank sincerely. > This is an interesting example, partly because it seems to me that C would be a better winner. I ran through some possibilities on the Ranked-ballot voting calculator at http://cec.wustl.edu/~rhl1/rbvote/calc.html, and got the following:
101: A 001: B>A 101: C>B A: Baldwin, Nanson, Raynaud C: Black, Borda (Other methods required a random tiebreaker). Strangely, if you reverse all the rankings, you get: 101: C=B>A 1: C>A>B 101: A>B>C A Baldwin, Nanson, Raynaud B Black, Borda Which means it made no difference to Baldwin, Nanson, or Raynaud. Black and Borda gave different answers for the reverse order, which seems logical. Now let's look at some possibilities for the second and third choice for those who picked A. 101: A>B>C 1: B>A>C 101: C>B>A A: Carey, Hare B: Baldwin, Black, Borda, Bucklin, Coombs, Copeland, Dodgson, Nanson, Schulze, Simpson, Small B looks like a good choice. Carey and Hare give a rather bizarre result, and strangely enough, if you reverse the rankings, you get every method picking C as the winner. If you pick C as the second choice for those that prefer A, you get: 101: A>C>B 1: B>A>C 101: C>B>A A: Baldwin, Carey, Hare, Nanson, Raynaud C: Black, Borda, Bucklin And yet reversing the order, you get A: Baldwin, Carey, Hare, Nanson, Raynaud (again!) B: Black, Borda, Bucklin Finally, if the votes are split as close to 50-50 as possible, you have 50: A>C>B 51: A>B>C 1: B>A>C 101: C>B>A A: Baldwin, Carey, Hare, Nanson, Raynaud B: Bucklin C: Black, Borda, Coombs Moving one vote from A>B>C to A>C>B makes Bucklin undefined but does not affect the others. Reversing the order still lets A win under Baldwin, Carey, Nanson, and Raynaud. Hare changes to candidate C, and Black, Borda, Coombs all change to B. The upshot is, with this example it looks like Borda and Black act the most logically through the range of possible rankings for B and C when voters pick candidate A for their first choice. (Of couse, right now I'm kind of punchy from pain pills, so I could be missing something. :D ) Michael Rouse ---- election-methods mailing list - see http://electorama.com/em for list info