Hello James,
On Apr 3, 2005, at 01:35, James Green-Armytage wrote:
Juho Laatu <[EMAIL PROTECTED]> writes:If someone is interested, I would be happy to see examples e.g. on how
the "SVM: MinMax (margins), PVM: MinMax (margins)" case (this one
should be an easy target) can be fooled in large public elections (with
no more exact information than some opinion polls on how voters are
going to vote).
I think that my 3/14 post provides such an example, and furthermore makes
it clear that such examples will be easy to find in general.
http://lists.electorama.com/pipermail/election-methods-electorama.com/ 2005-March/015125.html
my best, James
I'll write a short story explaining why I see the case of large public elections different from the case of individual strategic manipulation examples.
The example you used (in the 3/15 post) was:
Ex. 1: Sincere preferences:
46: A>B>C
44: B>A>C
5: C>A>B
5: C>B>A
Ex. 1: Pairwise comparisons:
A>B 51-49
A>C 90-10
B>C 90-10And the B voters then voted strategically 44: B>C>A and as a result B won the election.
My arguments are based on probabilities and the public nature and large scale of the election.
Let's say that these elections are some presidential elections in USA after a Condorcet based method has been taken into use. Candidate A could be from the republican party. Candidate B would obviously be from the democratic party. Candidate C is obviously not some centric compromise candidate since A and B voters seem to hate him. Let's say that he is a professional wrestler. The numbers obviously represent percentages of the total number of voters. The numbers are based on some opinion poll that has been performed some time before the election.
The democratic party is thus planning to vote strategically. I'll give some estimates to involved probabilities.
- probability of democrats giving a secret recommendation to all its supporters to vote B>C>A => low
- probability of democrats giving a public recommendation to all its supporters to vote B>C>A => low
- in both cases: probability of comparable number of republicans and others applying some strategy => high
(one can thus not trust that the outcome will be as planned)
- probability of sufficient number of democrats voting as they were told => low
(B will not win if more than 3 out of the 44 will not implement the ordered strategy (3 means a tie => 2 or less to win))
- probability of considerable portion of democrats voting sincerely even though they were told to vote strategically => high
- probability of many voters not understanding the strategy recommendation right or at all => high
- probability somewhat different voting behaviour than anticipated based on the opinion polls => high
- probability of some democrats not voting at all or voting republicans because they didn't play dirty strategy tricks before the election but emphasized the need to vote sincerely => high
- probability of C getting elected after everybody applying various strategies => low but increases considerably if democrats can make people vote as told
- probability of democrats getting their candidate elected by convincing few republicans to vote B => much higher than with strategic voting
- probability of democrats getting their candidate elected by convincing few C supporters to vote B => much higher than with strategic voting
- probability of democrats getting their candidate elected by convincing few C supporters to vote C>B>A instead of C>A>B => much higher than with strategic voting
(1 for a tie, 2 for a win)
Maybe there are also other reasons. Maybe some that give support to strategic voting(??). And maybe the probability estimates could be more accurate. But based on this story the probability of deciding to implement the strategy in general, and the probability of a successful outcome of this strategic voting case is in my opinion not very high.
What do you think the probability of a) democrats recommending their voters to use this strategy in these elections and b) probability of success of the strategy if implemented is?
My message is that although there exist strategic voting patterns that lead to unwanted results, one has to estimate also how serious those theoretical risks are in real life (in this case in large public elections).
If strategies are as difficult to implement and results as hard to achieve as in this story, maybe one could get good results by using some sincere voting method and telling voters that the voting method is well planned and made sincere to take their sincere votes into account in the best possible way. If one would in addition tell that using strategies most likely harms the voters' intentions rather than supports them and best voting scientists would confirm this, maybe people would be first of all happy with the new method and secondly also vote sincerely.
Best Regards, Juho
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