On Apr 26, 2005, at 13:15, James Green-Armytage wrote:
I have written on practical election situations since it seemed to me that that area has not been covered sufficiently on this mailing list.
You'll have to define "practical"
With practical election situations simply referred to the large public elections that have been discussed in this mail stream (there are also others). This is an election type where many strategies are not so easy to apply. US presidential elections are a special case of this generic category of elections. This "large public" category is of course a quite central category in real life.
Another type of election would be for example this election methods community arranging weekly elections (and daily test elections before the main election) on which one of a certain set of candidate election methods is the best. Negotiations trading with the elections of the following weeks would be allowed. I'm sure people would try every available strategy. Vulnerability to strategies would in this case be much more probable than in the large public election case (because of the expertise of the voters, small community, test elections, small "parties" that could negotiate their tactics, ability to make deals with enemies behind the screens, small number of candidates, known preferences of many voters).
Uncertain information is what makes the strategy problem in margins so
bad. If information was certain, then the CW would be known, and this
would simplify things somewhat. But if the true CW is not known, then both
sides have a potential incentive to bury, which is what leads us to
disaster.
Uncertainty has also some positive effects. If strategies lead to unexpected and unwanted results, then it is easy to tell voters that they should not try to vote strategically since that probably makes their situation worse, not better. This is closely related to the general very basic (non strategical) observation about Condorcet methods that voter whose sincere opinion is A>B>C>D need not vote A>C>D>B (to make the situation of the other strong candidate B worse) since that change doesn't make the A>B preference any stronger.
Sincere preferences as known by voters (Dem-Rep contest uncertain), with
utilities
46/44?: Dem >> Rep > wrestler (100, 5, 0)
44/46?: Rep >> Dem > wrestler (100, 5, 0)
5: wrestler >> Dem > Rep (100, 20, 0)
5: wrestler >> Rep > Dem (100, 20, 0)
Maybe this attitude ("my candidate is good, others not good at all") is common among people. Maybe one could assume that in some elections (e.g. when there is only one candidate from each party) even if the voters wouldn't be given the chance to mark ratings in the ballots.
Game matrix. Payoffs expressed as (Rep, Dem)
Dems bury Dems don't bury Reps bury wrestler wins (0, 0) Rep wins (100, 5) Reps don't bury Dem wins (5, 100) pairwise winner wins (52.5, 52.5 on average)
As far as I know, this game is called "chicken". Can you tell me how
people will vote, and who will win? I don't think that I can tell you who
will win, but I think that the wrestler has a pretty good shot.
Sounds like some game theoretic situation where both using the strategy may lead to a catastrophe to both but one applying it may lead to benefits. It is difficult to say to what kind of behaviour this leads to. I'm hoping that the risks would be stronger than the benefits and as a result people would avoid strategic voting. I'm not sure though.
People are also social creatures, and if the community encourages sincere voting, most people will follow that (which is enough to eliminate many strategies). Alternatively most voters would go for strategic voting, but that situation of the society would then be known to all.
Note that natural loops are not common in elections and artificial (=strategically created) loops are not that easy to generate. In the "no loop" situations Condorcet methods are quite immune to strategies and sensible people would vote sincerely. Maybe this would encourage sincere voting as a rule in the society.
Wrestler supporters' strategies are also interesting. They have different interests depending on which of the D/R strategic voting scenarios takes place. Complex mixture of strategic voting could lead to electing the "sincere winner".
Making all the democrats understand the burying strategy requires also systematic teaching,
Not necessarily. Imagine a Bush>>Kerry>John Doe voter, who marginally
prefers Kerry over John Doe but hugely prefers Bush over Kerry. Kerry is
obviously the main competition to Bush. Isn't there something
instinctively unattractive about ranking Kerry in second place? I think
so. Even if you don't understand the method at all, instinct can be to do
as much harm as possible to the main rival to your favorite viable
candidate.
You almost give the generic simple rule (as an alternative to party or press led strategies) for normal voters that I asked for. The rule could be "put the serious competitors last in the ballot". This rule could help in some situations but maybe (hopefully) it would still bring more harm than benefits if used by people who don't know when it is likely to bring results.
Btw, it would be good to get some estimates on how probable it is that this kind of basic strategies make the results better/worse (when applied without coordination and without good understanding about the preferences of the voters). Note also that the strategy where people intentionally create a loop between the candidates of a competing party is quite risk free and from this perspective more problematic than the burial type that we are discussing here.
Maybe they will stop voting, or maybe they would campaign for some other voting method than Condorcet to be used,
Or perhaps a more strategy-resistant variant such as CWP or AWP?
Yes, that is also possible, especially if experts tell that that would help.
It's
probability of improvement times strength of improvement minus probability
of harm times strength of harm
Yes, this is a valid formula.
Of course, in an election with a large number of voters, the change in
probabilities would not be anywhere near so large, but you should get the
idea anyway.
Yes. In large elections this probably means that you and a considerable number of people who share your opinions will vote in the described way to achieve the results.
If there are three candidates with exactly equal amount of support it is probably too difficult to guess the direction of the cycle and correct strategy (there is no weak candidate that could be used to bury a strong candidate).
However, after I proposed CWP and AWP, Chris
Benham took up the idea of a margins version of both, and I haven't been
able to talk him out of the "approval margins" method as yet. I could dig
up some of my postings on the subject if you like...
I can make some mail searches. Not too many mails on this topic yet.
Smith-efficient
methods have some extremely significant advantages over all other methods
Smith-minmax excluded or included? I.e. is Smith efficiency the exact criterion here?
they should each be assumed to be guilty of extreme strategic vulnerability until proven innocent
Fatal strategic vulnerability is of course a show stopper, but it appears not to be easy to tell which threats are fatal in real life.
The problem with margins is that the relatively stable counterstrategies like the WV one mentioned above don't serve to deter it.
But here I make some probabilistic calculations on how many people would be able to apply the correct strategies, and how likely these strategies would be needed, and how likely it is that they would cause harm, and thereby make difference between margins and WV significant. I put also some weight to the sincerity of margins (maybe more because of the psychological effects of than because of the fact that it sometimes would elect a better candidate).
In those voting methods one could get some strategy defence benefits also with sincere votes (that you could also call an "unintentional counterstrategy").
Yes! That's one of the best things about cardinal pairwise. Sincere ratings very strongly tend to make burying strategies unprofitable.
Agreed. Sincere votes are much better than the need to apply strategies.
Best Regards, Juho
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