I've now talked about Monotonicity and the lesser-of-2-evils problem. Now I want to briefly mention a few other things: Were you here when we were discussing social utility (SU)? Say we rate the candidates according to how much we'd like them to win. Those are our "sincere ratings" of the candidates. They measure how much good the candidates would be expected to do for us if they won. Say, when someone wins, we add up everyone's sincere rating of that winning candidate. That's his "social utility", abbreviated "SU". SU matters, because: Say there's going to be an election, years down the line, by a method that hasn't been chosen yet. We hope it's a good method. A method's average SU is the average of the SU of its winners over a long series of elections. Now, say there's reason to expect Approval to have a higher average SU than IRV. That means that _your_ expectation, estimated now, for that future election, is better if the election will by by Approval than it would be if the election will be by IRV. Well, guess what? In all the simulations I've heard of, IRV does significantly worse than Approval. These are "zero-info" simulations, in which it's assumed that voters don't have polling data or winnability information about the candidates. But don't let that make you think that that invalidates the results. IRV advocates always claim that people will vote sincerely anyway, just as they do in our zero-info simulations. And, when winnability information is added, Approval's average SU score can only improve. Samuel Merrill describes his simulation study in his book _Making Multicandidate Elections More Democratic_. Approval reliably & robustly did much better than IRV. As we add more candidates, IRV does even more dramatically worse. If we have the candidates distributed more tightly about the voter median than the voters are--as candidates tend to try to do--that makes IRV do worse still. Pairwise-count methods, such as Condorcet's method get the top scores in average SU in zero-info elections. With Condorcet's method we can expect those high scores to continue even when information is available. Another thing: Recently on this list you may have noticed some discussion about how _bad_ an SU score the winner can have, with various methods. It's a new subject here, but so far it's turned out that IRV can do a lot worse than Approval, especially as we add more candidates. In regards to how low can be the SU of the winner by that method. I hope I've clarified why we don't want IRV. But by all means if you have any questions or comments, or agreements or disagreements, be sure to let me know. Mike Ossipoff _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com.
