Monotonicity: Difference between revisions
m
Reword weasel-worded phrases about Australia
m (Adjust section headings for Woodall's criteria) |
m (Reword weasel-worded phrases about Australia) |
||
Line 93:
===Australian elections and by-elections===
Since every or almost every IRV election in Australia has been conducted in the black (i.e. not releasing enough information to reconstruct the ballots), nonmonotonicity is difficult to detect in Australia, even though thanks to the Lepelley ''et al'' probability estimates it seems safe to say that it must have occurred in over 100 of their elections.<ref
▲has been conducted in the black (i.e. not releasing enough information to reconstruct the ballots), nonmonotonicity is difficult to detect in Australia, even though thanks to the Lepelley ''et al'' probability estimates it seems safe to say that it must have occurred in over 100 of their elections. (The policy of Australia's election authorities not to release this data
However, for the [[Australian federal election, 2010]], one article was aware of the non-monotonicity possibility: [http://andrewnorton.info/2010/08/16/why-labor-voters-in-melbourne-need-to-vote-liberal/ Why Labor Voters In Melbourne Need To Vote Liberal]. In 2009, the theoretical disadvantage of non-monotonicity worked out in practice in a state [[by-election]] in the [[South Australia]]n seat of [[Electoral district of Frome|Frome]]. The eventual winner, an Independent who was a town mayor, scored only third on the primaries with about 21% of the vote. But since the [[National Party of Australia]] scored 4th place, their preferences were distributed beforehand, allowing the Independent to overtake the [[Australian Labor Party]] Candidate by 31 votes. Thus Labor was pushed into third place, and their preference distribution favoured the Independent, who overtook the leading [[Australian Liberal Party]] candidate to win the election. However, had anywhere between 31 and 321 of the voters who preferred Liberal over Labor and Independent switched their support from Liberal to Labor, it would have allowed the Liberal to win the IRV election. This is classic monotonicity violation: the 321 who voted for the Liberals took part in hurting their own candidate.<ref>http://blogs.abc.net.au/antonygreen/2011/05/an-example-of-non-monotonicity-and-opportunites-for-tactical-voting-at-an-australian-election.html</ref>
Line 124 ⟶ 121:
== Footnotes ==
=== Notes ===
{{reflist| group="nb"}}
=== Videos ===
* [https://www.youtube.com/watch?v=OI232JSDwDg "Voting Theory: Monotonicity Criterion Using Instant Runoff Voting" - Mathispower4u] - posted to YouTube on August 22, 2013. "''This video explains the Monotonicity Criterion and how it can affect the outcome of an election when using instant runoff voting.''"
| |||