Tactical voting: Difference between revisions
Added note about multiwinner strategyproofness usually being impossible
(Changing the introductory paragraph to note that all non-dictatorial voting systems rely on some tactical voting, as shown by the Arrow's theorem, Gibbard's theorem, and the Gibbard-Satterthwaite theorem.) |
(Added note about multiwinner strategyproofness usually being impossible) |
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=== Information in strategic voting ===
An important thing to consider with strategic voting is how difficult it is for voters to figure out how to strategically vote. Distinctions are made between zero-info strategy (strategy that can be applied to get a better result without any information of other voters' preferences) and strategies that revolve around having various amounts of (accurate) polling information. In addition, the likelihood of a strategy working, and the risk/amount of harm (see [[utility]]) coming from it backfiring is also studied. Another common measure of a voting method's resistance to strategic voting is manipulability, which measures how often a voter or group of voters can vote strategically to improve the election results from their point of view.
=== Multi-winner methods ===
The Duggan-Schwartz theorem extends Gibbard-Satterthwaite to multi-winner voting methods. It states that either some candidates can never win, or some voters are treated differently than others, or the outcome consists of some group of voters' first preferences, or the method is manipulable. It therefore isn't possible to escape tactical voting by making the method elect multiple winners (unless it elects so many that everybody's first preference is elected).
==See also==
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