2011/7/8 Toby Pereira <tdp2...@yahoo.co.uk> > > The thing about SODA is that it's harder to "get" than Approval Voting. I haven't exactly read through all the posts on it here thoroughly but I've looked at the page - http://wiki.electorama.com/wiki/Simple_Optionally-Delegated_Approval - and I do find myself thinking "What?" All of its advantages over other systems may be within the posts on this board, but they are not that clear to me from reading the article. The method is explained and also the criteria it satisfies but I'm not happy that I've been convinced why it works. > > Why are the votes only delegable if you bullet vote (or is that obvious)?
Because if you vote for several, which one would get to assign the delegated votes? > > Also it seems like a lot of work for just the people who bullet vote (and also allow delegation). Do we know in practice what proportion of people do bullet vote in Approval Voting? Bullet voting in Bucklin is strategically equivalent to bullet voting in Approval. In fact, approval would have if anything more bullet voting than Bucklin, because Approval gives no way except bullet voting to express a unique first preference. A quick search finds two results for bullet voting in Bucklin: "In Alabama, for example, in the 16 primary election races that used Bucklin Voting between 1916 and 1930, on average only 13% of voters opted to indicate a second choice." and in a Spokane mayoral election "568 of the total of 1799 voters did not add second rank votes". That's a broad range, but certainly enough to see that it's significant. > Might SODA reduce this number anyway? > SODA takes away most of the strategic motivations NOT to bullet vote, so if anything it would lead to more bullet voting. > > From the page: "If any candidate has an absolute majority at this point, or > cannot possibly be beaten by any other candidate using the delegable votes > and candidate rankings available, then they win immediately." Does absolute > majority just mean over 50%? > Yes. > But with Approval 50% isn't a particular threshold. > That's right. However, if most votes are bullet votes, then it is. Also, it is important when selling a system to just be able to say "majority wins" and not have to qualify it. Sure, there are people who are willing to listen to your explanation of why not, but there are a lot of people who aren't. > You can get over 50% and still be beaten. Maybe I'm just unclear on > "absolute majority", but it's been put as distinct from "cannot possibly be > beaten by any other candidate using the delegable votes and candidate > rankings available". > That's right, these are two separate possibilities, but the rule is deliberately stated in a manner so that a reader who wasn't as aware as you would just read this as one case, so they don't feel that there are too many special cases. > > And it still seems strange to me that candidates pre-declare their > delegation order but then still get to negotiate. Yes, there's an > explanation, but I'm not really sure I get it. "The system as it stands > allows them to see, after the votes are counted, which of them deserves to > win. That one will not delegate their votes, and the other one (of > necessity) will." Couldn't there be a way in the system to decide who > deserves to win (e.g. based on who would get more votes after the delegation > or who had more to start with)? > In real-world elections, with no more than a half-dozen viable candidates with the rest getting tiny handfuls of votes, it would be quite feasible to work out the unique rational strategy and have the system do it for them. This is not done for two reasons: 1. To allow a "foregone kingmaker" scenario. A non-winning candidate with a large pile of votes deserves to be a focus of media attention for a few days, and has earned the right to make minor and reasonable demands (on the order of a cabinet seat or two for their party, to serve at the pleasure of the executive). Remember, because the delegation order is pre-declared, the eventual result is almost fore-ordained; minor candidates do not have the power to get too greedy in their demands. And if they take the radical step of NOT sharing their delegated votes in the rationally-correct fashion, their voters would justly want to know why - and their party would suffer if they didn't have a good explanation. 2. As a check on the possibility of strategic declared rankings. In a 1-dimensional 3-candidate scenario, imagine one wing buried the center candidate and managed to be the apparent "rational" winner thereby. If the other candidates realize this, they can keep this trick from working, but only if their "rational" strategy is not automatic. Also, just out of interest, is there a multi-winner version? > SODA outputs approval ballots (which can also be considered as 3-rank Bucklin ballots). Any proportional method with approval ballots as an input can then be used. With the number of dimensions on which such systems can vary, I could easily list two dozen distinct methods (although results would tend to agree across many of them). JQ
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