Hi Juho, Various replies follow, on the subject of voter strategy. >Condorcet is close to a dream come true in the sense that it almost >provides a perfect solution that eliminates all strategies from >elections and frees people to giving sincere votes only.
This is true only in terms of the"compromising" strategy, which Condorcet methods minimize. However, they open the door to the "burying" strategy, which does not exist in plurality or IRV. I already defined these terms for you. See also Blake Cretney's web site, for a list of which methods are haunted by which strategies. http://condorcet.org/ The burying strategy is more of a theoretical phenomenon than the compromising strategy, because methods that invite the burying strategy are not yet used in large-scale contentious elections. Hence it's hard to say exactly how common it will be. However, I feel that we can say with some confidence that it will be more common in some methods than others. E.g. more common in margins than winning votes; more common in winning votes than in any of the following: cardinal pairwise, approval-weighted pairwise, wv with CWO or AERLO/ATLO. Have you read my 3/14 post yet? http://lists.electorama.com/pipermail/election-methods-electorama.com/2005-March/015125.html >I would like to see concrete examples of cases >where in _real_world_election_situations_ strategical voting is a real >risk (and opportunity). It's hard to find real-world data about voter behavior given voting systems like Condorcet that are predominantly theoretical. I suppose we could try to take ranked ballots from a STV elections and see what sort of strategic possibilities would have existed if it had been a Condorcet election instead. That's not quite the same thing, but it might be fun anyway. >If such cases are not clearly demonstrated for >each strategy eliminating fix/method, then we take the risk of picking >an election method that has features that are good in theory but never >needed in practice. It's far better to err on the side of caution, especially when the integrity of the electoral process and the credibility of pairwise count methods are at stake. > > >Summary: Simple examples of use cases where strategies are a real >threat are needed to justify adding such defense mechanisms in the >election system. I have provided several made-up examples along these lines. If you want real examples, you have to wait for the method to be adopted for contentious elections. > >Some classifications that may be useful when analysing the seriousness >of different voting strategy threats: ... Your "a" through "k" code system is perhaps not necessary, but the questions you are asking are largely the right ones to ask. >One example strategy that I find interesting (because it is not so easy >to ignore) is one where voters try to create a loop that includes only >the candidates of a competing party. All voters add at the end of their >ballot a list of candidates of the competing party in certain order. Do >we need to defend against this? Yes, among other forms of the burying strategy. >What would be the best method? To begin with, the method should be Smith-efficient. That way, if none of the strategizers' party's (party B's) candidates actually beat the other party's (party A's) candidates, the winner will come from party A. With minimax, party A could be a party of clones with a mutual majority, and still fall victim to party B's strategy. Second, the method should at least be a wv method, if not something stronger (cardinal pairwise, AWP, CWO, AERLO/ATLO, etc.). I've explored this idea in other places, and will continue to do so... >(Note >btw that there are also methods outside the vote counting phase. If we >make the ballot forms such that voter can only use limited number of >preference values (e.g. from 1 to 5) (several candidates can be given >the same value), then there is not much space for making such loops.) There are better ways to curtail strategy; reducing preference spaces is not necessary. > >Another interesting area is the recent discussion on this mailing list >on withdrawal after the elections. This is a very risky case since now >everyone knows exactly what the votes are unlike before the election >when they probably only had wild guesses and few Gallups. The concept of CWO (candidate withdrawal option) is that there is only one public vote, but after the initial tally, candidates have the option of having a new tally with their names deleted from the ballot. We can only hope that the candidates will usually have enough information to tell sincere cycles apart from strategically created cycles, and that they will primarily use the CWO to correct strategically altered results. CWO is one of the more rough anti-strategy measures, but it has the advantage of not complicating the ballot and keeping the tally method proper as simple as possible. my best, James > http://fc.antioch.edu/~james_green-armytage/voting.htm ---- Election-methods mailing list - see http://electorama.com/em for list info