Talk:Spoiler effect

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Alternative voting systems which avoid the spoiler effect include instant runoff voting, also known as single transferable vote.

This is wrong on two accounts:

  1. IRV and STV are not the same thing. The first is a single-winner system; the second is a multi-winner system. The second reduces to the first in the case of a single district.
  2. IRV and STV can suffer from the spoiler effect. For example, if the "p-ist" vote was split between 3 p-ists, the most popular and "major party" p-ist could be eliminated early, even though they would handily beat the winning q-ist.

[edit] IRV & Spoiler Effect

IRV is free from the spoiler effect, if implemented correctly, because it meets the Independence of Clones Criterion (ICC). See: [1]

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I've read many other places that IRV only stops the spoiler effect when the third party is weak. In the scenario where the third party becomes almost an equal, the spoiler effect can come back into play. For example if Nader was looking like he might be almost an equal with Bush and Kerry, and we were under IRV, liberals might be afraid to vote for Nader because if it was a runoff between Bush and Nader it would seem more likely that those who ranked Kerry first instead of Nader would put Bush second.

IRV isn't free from the spoiler effect at all. In order to be "free" from the spoiler effect, it would have to be free from Independence from Irrelevant Alternatives Criterion (IIAC). It's not. It's not even compliant with relaxed versions of IIAC, such as Local IIAC. --- RobLa 03:51, 12 May 2004 (UTC)

[edit] Stupid question

I always knew this as vote splitting. How is it different? (add an explanation if it is, add to the merger if not) 142.177.168.90 14:15, 18 Jun 2004 (UTC)

Yes, this should be merged with vote splitting. However, it should not be merged with Independence of Irrelevant Alternatives - the two are related but different subjects.

I would disagree that they should be merged.
First, I believe it would be accurate to say that Vote Splitting is related to the Independence of Clones Criterion (http://condorcet.org/emr/criteria.shtml).
The spoiler effect can refer to either independence of irrelevant alternatives and Vote Splitting and I have seen the terminology used in both contexts.
In the case of independence of irrelevant alternatives, one can think of candidate B as a spoiler for candidate A if, when candidate B was removed, candidate A wins the election.
The situation is different when it comes to clones/vote splitting. If candidate B & A split their votes, it does not imply that either candidate would win the election.
Ericgorr 23:09, 10 Nov 2004 (UTC)
In that case, should the spoiler effect article be a disambiguation page? Tim Ivorson 13:35, 11 Nov 2004 (UTC)

[edit] I think IIA rather than vote splitting

I think that the "spoiler effect" is better understood as sensitivity to irrelevant alternatives rather than sensitivity to clones in the form of vote splitting. Given that, Condorcet methods reduce the spoiler effect by only being sensitive to IA's when there is no CW, and approval arguably eliminates the spoiler effect under certain assumptions. --Hermitage 06:33, 14 July 2005 (UTC)

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