I think that this kind of investigation of strategy in realistic monte-carlo simulations is important. Two comments:
1. Do you plan to share your source code? I'd encourage you to do so, preferably under some kind of open-source license (including just public domain). 2. I've been thinking of how to extend Yee diagrams to show strategic vulnerabilities. So far, I'm thinking of starting with a interactiveone-dimesional Yee diagram<http://zesty.ca/voting/voteline/> with three candidates, and using method DNA to show separate strategic and counterstrategic possibilities in separate lines. In those terms, runoff-style methods (including my recently-developed MCA-Asset and GMCA) are somewhat confounding, because a first-round strategy doesn't carry over into the second round, so they effectively expand the range that the DNA must cover to include both rounds (although I think that certain ballots, such as A>B>C and then C>B>A, can be discounted). For your simulation, I wonder if it would be possible to include such methods, by assuming that voters would always be honest in the second (two-candidate) runoff round? Of course, pushover strategies and counterstrategies would become important for such systems. Jameson 2011/3/8 Kevin Venzke <[email protected]> > Hi Kristofer, > > --- En date de : Mar 8.3.11, Kristofer Munsterhjelm <[email protected]> > a écrit : > > > I'm working on another simulation. It is for > > 3-candidate elections and > > > allows these ballot types (if the method also allows > > them): > > > A (bullet vote) > > > A>B>C (strict) > > > A=B>C (tied at the top) > > > A|B>C (middle candidate ranked but "disapproved") > > > > > > This should be enough to handle most rank or 2- or > > 3-slot methods. > > > > > > The voters have some intelligence, and polling > > opportunity, so a method like "elect the guy with the most > > last preferences" should do just as well > > > as Plurality. > > > > > > They can be a little superstitious, especially with > > random methods: e.g. > > > Random Ballot isn't perceived as strategy-free. And > > there can be e.g. > > > burial in IRV from voters who never managed to be > > harmed by it. > > > > How is this superstition (on the one hand) and intelligence > > (on the other) implemented? > > Well, I don't want voters to be superstitious. It's an accident. They are > trying to find the best way to vote. But they may latch onto something > that is not sincere, because they have no concept of that. > > > Also do voters who favor one of the candidates have greater > > intelligence than those who favor others? > > I'm not sure where this thought comes from, but I think the answer is no. > > It is bloc-based, and a bloc votes together. So a large bloc could be > said to be able to "coordinate" better. If there are few blocs (which is > how I currently test it) it may not be very fair in this sense. > > > If you had a > > computer that could strategize on behalf of every voter, you > > would in effect have a DSV method, and the DSV method might > > not be all that bad. > > It is sort of like that. It's based on polling. There's no difference > between a poll and the actual election. So, voters have a good idea how > other voters think they should vote, in the sense of how to respond to > those votes. Voters may in effect decide on a "mixed strategy." > > It's possible to imagine that at the last minute voters in reality could > decide to switch their polling vote to something else for the actual > election. Could that be realistic? Those voters have to communicate their > plan to each other without anyone else learning of it. My sim assumes > that is not possible. > > > However, if one of the > > parties/candidates are better at coordinating their voters > > and executing strategy, they may snatch the victory from the > > "honest" winner. Thus, the worst case in strategy might be > > when all strategize (in mutually limiting scenarios like > > Plurality's lesser evil situation), or when only some do, > > and if you want to check the impact of strategy, you might > > want to check both cases. > > I think I've mostly covered this, but let me know if not. > > I am very interested in what strategies are used. Four are detected: > Compromise (involving reversal), compression, truncation (in the sense > of bullet-voting), and burial. ("Push-over" strategy is possible but would > be detected as compromise, and I'm not sure how to get around that.) > > Occurs to me that there's no "abstain" strategy, which might be > interesting. A little tricky to add though. > > > > Anyway, I'm interested in methods that might pose a > > challenge to my voters (such as perhaps deterministic > > methods that fail majority favorite; > > > I have very few of these), or methods that might > > actually be good... > > > > Every positional method except Plurality fails majority > > favorite. Range fails it as well, and Approval might if you > > interpret it a certain way. > > Yes, all those are implemented, as well as strictly-ranked Borda. As an > example of something odd: Once when playing with a simulation years ago > I came up with the idea of taking the pairwise comparison between the > approval winner and the candidate with the greatest opposition (approval > or pairwise, I don't remember) to him. It sounded nice but it failed > majority favorite. > > > You might also test Random Pair and Hay, if that's feasible > > within your simulator. Both are strategyproof. Random Pair > > picks two candidates at random and elects the one who beats > > the other Pairwise. Hay is described here: > http://www.spaceandgames.com/?p=8 and there's a (very > > complex, cloneproof?) iterated version at > http://www.panix.com/~tehom/essays/hay-extended.html . > > Random Pair is on the to-do list, but I don't think Hay is feasible if > it requires a very fine ratings ballot. Can we do Hay with 3-slot ratings > (normalization required)? I'll check. > > Another example based on Forest and Jobst's paper: What if the first- > preference winner wins if he gets (say) 2/3rds of the vote, else Random > Ballot? I'm pretty sure this would stump my voters with the number of > polling iterations I currently use. > > Thanks for your thoughts. > > Kevin > > > > ---- > Election-Methods mailing list - see http://electorama.com/em for list info >
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