Vote splitting: Difference between revisions
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Psephomancy (talk | contribs) (clean up (AWB), typos fixed: be heavily dependant on → be heavily dependent on, ’s → 's (3)) |
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The biggest issue with a single-mark ballot is that it can cause a high amount of vote splitting. It is particularly problematic in [[single member plurality]] elections. However, other systems that still use a single-mark ballot such as [[Runoff voting]] still have vote splitting.
A standard example of vote-splitting is when two candidates are similar, so they each get half the votes they would if the other were not running. This is a good example of failing the [[Independence of clone alternatives]] criteria. Another issue is that the
== [[Preferential voting
The major advantage of such a system is to eliminate the standard forms of vote splitting which are present in [[Single-mark ballot]] systems. This effectively eliminates issues that give rise to the [[wasted vote]] or the [[Favorite betrayal criterion
Unfortunately, it can be proven mathematically that ranked ballots cannot produce a communal preference without serious issues. There are no non-dictatorial rank voting systems that satisfy both [[Pareto Criterion]] and [[Independence of irrelevant alternatives]] in a way that can produce such a communal preference. This is known as [[Arrow's impossibility theorem]] and states that when voters have three or more candidates, no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide (complete and transitive) ranking while also meeting [[Pareto Criterion]] and [[Independence of irrelevant alternatives]].{{redundant}} Both [[Pareto Criterion]] and [[Independence of irrelevant alternatives]] are well-supported requirements by experts and the general public. The main reason that ranked ballots are still proposed as a solution to vote splitting is that the general public is not aware of the [[Arrow's impossibility theorem]]. It is mathematically complex and somewhat counter-intuitive in many systems so is easily ignored. There is a large discrepancy between what the voter impact is perceived to be and what occurs in implementation.
== [[Cardinal voting systems
Cardinal voting systems do not have vote splitting. However, some [[Multi-Member System]] can still fail criteria related to
== Relation to [[Proportional Representation]] ==
Vote splitting is often conflated with [[Proportional Representation]] but they are completely distinct concepts. Vote splitting is related to strategic or expression issues at the time of filling out a ballot by a voter. [[Proportional Representation]] is a measure of the outcome of an election. The relationship is that vote splitting is a major cause of reduced [[Proportional Representation]]. Systems designed to achieve high [[Proportional Representation]] but that still use [[single-mark ballot]]s often do not reduce the amount of vote splitting but instead mask its effects at the partisan level. A [[Mixed Member Proportional
Another confusing point is that [[Proportional Representation]] is most clearly defined for [[Single-mark ballot]]s but [[Single-mark ballot]]s have the largest problem with vote splitting. When one wants to move to a system without vote splitting to improve [[Proportional Representation]] a problem is encountered in that it can no longer be clearly defined.
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