> Are there cases where the winner according to strategically cast ballots > is a better choice than the winner according to sincere ballots?
Here's one such example, assuming the CW is a better choice, in cases where IRV elects someone else... Sincere preferences: A>B>C:25 A>C>B:14 B>C>A:15 B>A>C:14 C>A>B:10 C>B>A:22 Condorcet: B wins A>B:25+14+10=49 B>A:15+14+22=51 A>C:25+14+14=53 C>A:15+10+22=47 B>C:25+15+14=54 C>B:14+10+22=46 Sincere IRV: A wins A:39,C:32,B:29 A:53,C:47 Strategic IRV: B wins A>B>C (same) A>C>B (same) B>C>A (same) B>A>C (same) C>A>B -> A>C>B C>B>A -> B>C>A A>B>C:25 A>C>B:14+10=24 B>C>A:15+22=37 B>A>C:14 B:51,A:49 Yes, there are different strategies that could be tried, such as A>C>B changing to C>A>B ... but then A>B>C would simply switch to B>A>C and B wouls still win. Perhaps the fact that B is the CW guarantees that there will always be a strategy that allows B to win under IRV as well? That would be an interesting fact, if true. Also, this is obviously an unrealistic scenario in that organizing such large-scale strategic voting is infeasible in the real world, due to limited information. HOWEVER -- if a full theory of optimal strategies could be worked out, it might be interesting to devise a two-stage election method that utilizes sincere ballots as inputs, then determines what the "correct" strategic ballot would be for each voter (assuming perfect information.) -Bill Clark -- Ralph Nader for US President in 2004 http://votenader.org/ ---- Election-methods mailing list - see http://electorama.com/em for list info
