Hello James,
You wondered how familiar I am with different strategies etc. I have studied the voting methods for quite some time and I have visited also Blake Cretney's web site. I think I know most of the basic stuff but unfortunately have not had time to follow all the details of the discussions on this mailing list, so I don't master all of the abbreviations of three and four letters.
On Mar 17, 2005, at 12:59, James Green-Armytage wrote:
Have you read my 3/14 post yet?
http://lists.electorama.com/pipermail/election-methods-electorama.com/ 2005-March/015125.html
I'm off-line at the moment so I can't check. I guess yes but if I haven't, I'll do that.
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.
Yes, that would be a good check against real life data. I'd be interested in doing the tests (at least in theory) so that before opening the ballot files we would read the local newspapers from the time before the elections and then make strategy recommendations to different type of voters. It is important that the strategies would be applied before knowing the actual outcome of the election and the ballots. This method would help seeing which strategies can be applied in real life an which not.
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.
I agree that risk analysis must be done and serious risks must be eliminated (if possible) by selecting appropriate voting methods.
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.
Made-up examples are fine with me. What I often would like to see more is to make the voters less clairvoyant and limit their information better to what they are likely to have available in a real voting situation. It is thus not enough if some voting result could have been manipulated by appropriate strategical voting. The strategy must be usable also in real life to be a real threat.
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.
I'm particularly interested in strategies that can be implemented without any prior knowledge of the expected outcome of the election. That's why I picked this strategy. This category of strategies is dangerous in the sense that it makes my target/hope of keeping the voting methods close to the best sincere methods harder to achieve.
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.
Let's say that because of the applied strategies both A and B candidates have a loop within the party. If party B is a bit smaller than party A, then the loop within party A must be weaker than the loop within party B. In this case there would be no need for a defence (=> also basic MinMax would be fine).
I'm worried about the possibility that all voters would have to apply strategies in their ballots or otherwise they would lose the election. A voting method that forces people to follow complex unintuitive strategies surely is not a good voting method. If only party B applies the strategy, then party A could lose the election if basic MinMax was used.
I have sometimes played with the idea that if there are rules that try to eliminate party internal loops, maybe those rules should apply to parties only and not to other, maybe sincere loops. One could solve this by using a method that takes into account which candidates have been declared as belonging to the same party. Loops among them would not be used against them. I don't know if such methods have already been discussed somewhere. I haven't analysed these well enough to have any firm opinon. And I understand that there are also malicious burying loops between that involve several parties.
One big weakness of the loop voting strategy is that one has to agree how to construct the loop. Is it ABCDA or is it ADCBA or something else. Also voters have to be quite educated to understand that they should pick a random starting point of the loop and create the loop based on this information. In large public elections these problems may be enough to make the strategy useless and defensive methods unnecessary.
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...
I can't comment since I can not estimate the risks and need for defence yet.
There are better ways to curtail strategy; reducing preference spaces is
not necessary.
I agree that reducing preference spaces is quite violent. On the other hand in practical elections sometimes simple ballots are a benefit. But maybe it is also simple enough to write a ranking number next to each candidate.
Best Regards, Juho
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