Center squeeze: Difference between revisions
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The effect is not limited to 3 candidates: The more candidates there are crowding the center, the less likely they are to win.
Voting systems which have serious problems with center squeeze include [[IRV]] and two-round [[runoff voting]]. Systems which can do either well or poorly in a center squeeze situation include most [[graded Bucklin]] systems and [[score voting]]. Systems which generally do well with center squeeze include [[Condorcet systems]] (although in some cases, a center squeeze scenario could become an opportunity for one of the wings to use burial strategy and create an artificial Condorcet cycle).▼
== Example ==
For example, on a 2-dimensional political compass with 3 candidates, candidate B is the Condorcet winner and utilitarian winner, but is squeezed out by A and C on either side:
[[File:2D election example A vs B vs C.png]]{{Graph:Chart|width=200|height=150
|xAxisTitle=Candidates|yAxisTitle=Votes|type=rect
|x=A, B, C
|y=1031, 861, 1108
|colors=#1f77b4, #ff7f0e, #2ca02c
}}C would win under a single-round of FPTP, but if there is a runoff, then more of B's votes transfer to A and make A the winner:
[[File:2D election example A vs C.png]]
{{Graph:Chart|width=200|height=150
|xAxisTitle=Candidates|yAxisTitle=Votes|type=rect
|x=A, B, C
|y=1619, 0, 1381
|colors=#1f77b4, #ff7f0e, #2ca02c
}}
However, neither A nor C are very good representatives of the electorate.
== Prevalence ==
Voting systems which have serious problems with center squeeze include [[First Past the Post electoral system|FPTP]], [[IRV]] and two-round [[runoff voting]].
Systems which can do either well or poorly in a center squeeze situation include most [[graded Bucklin]] systems and [[score voting]].
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