Voting system criterion: Difference between revisions
→Essential criteria
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Some criteria are very widely agreed to be important. Examples:
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* [[Clone independence]]: Replacing a candidate with multiple near-identical candidates shouldn't change who wins.▼
* [[Pareto]]: If everybody prefers X to Y, then the method's ranking should also prefer X to Y.
* Anonymity/Fairness: All candidates and voters should be treated identically.
=== Desirable criteria ===
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* [[Participation criterion]]: Showing up to vote shouldn't make a candidate you prefer lose.
* [[Summability criterion]]: All the data the method uses to call the election should be expressible as a short summary.
▲* [[Clone independence]]: Replacing a candidate with multiple near-identical candidates shouldn't change who wins.
Sometimes desirable properties or criteria are called desiderata.
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Here are some criteria often touted by advocates of [[majority rule]], split into categories of "widely agreed on" and criteria which are more polarizing:
[[Majority criterion]], [[Mutual majority criterion]], [[Majority loser criterion]], [[Droop proportionality criterion]], [[Condorcet criterion]], [[Smith criterion]], [[Condorcet loser]]
=== Proportionality-related criteria ===
[[Proportionality for Solid Coalitions]], [[Justified representation]], [[Perfect representation]], [[Stable Winner Set]], [[Quota rule]]
=== Strategic voting-related criteria ===
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These generally are considered essential and basic features of any voting method
[[Discrimination axiom]], [[Homogeneity criterion]], [[Scale invariance]], [[Anonymity criterion]], [[Neutrality criterion]]
=== Miscellaneous criteria ===
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'''Examples of relative criteria:'''
*[[Monotonicity criterion]], [[Participation criterion]], [[Later-no-harm criterion]], [[Later-no-help criterion]], [[Sincere Favorite criterion]], [[Independence of irrelevant alternatives]], [[Strategic nomination|Independence of clones]], [[Neutrality of Spoiled Ballots]], [[Reversal symmetry]]
== Other systems ==
=== Proportional Representation ===
[[Proportional representation]] is the general idea that groups of voters with shared preferences should be able to win an amount of representation in a multi-winner body (a legislature) proportional to how large they are. In partisan PR methods, proportionality can be measured using various measures of how well a party's seats matched up to its share of votes. For nonpartisan methods, there is disagreement on how to measure or quantify PR.
=== Rated ballot adaptations ===
Several criteria have rated-ballot or other adaptations that may make more sense in certain contexts. For example, the [[majority criterion]] says that a candidate preferred by a majority over all other candidates must win. The [[Majority criterion for rated ballots]] further requires the majority to give this candidate the highest score. It can be argued that a voter who gives their favorite candidate less than full support (i.e. didn't do [[normalization]]) doesn't deserve full power, so this modification to the criterion ensures that only a strategic or strongly supportive majority gets their way. Similar adaptations can be made to any criterion involving voter preferences determining who should win, such as [[PSC]], the [[plurality criterion]], [[
== References ==
[[Category:Voting system criteria|*]]
[[Category:Voter strategy]]
<references />{{fromwikipedia}}
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