Proportional representation: Difference between revisions
→Proportional Representation Criteria
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Since the standard definitions of Proportional Representation do not apply to nearly all modern systems it has become common to define proportional representation in terms of passing some sort of criteria. There is no consensus on which criteria need to be passed for a parliament to be said to be proportional.
[[Proportionality for Solid Coalitions]] Criterion
If a sufficiently-sized group (generally at least a Droop or Hare quota) prefer a set of candidates above all others, do at least a proportional number (being the number of quotas the group comprises rounded down to the nearest integer) of candidates from that set (supposing there are enough of them) get elected?
===Proportional (Ideological) Representation Criterion===
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===Comparison===
[[Proportionality for Solid Coalitions]] is praised for ensuring that voters get what would intuitively be considered an at least somewhat proportional outcome, but is criticized for focusing too much on giving a voter one "best" representative, rather than letting that voter have influence in electing several representatives.
Many of the properties of these systems can be derived from their party list simplifications. The [[Balinski–Young theorem]] implies that not all desirable properties are possible in the same system. Theile type systems reduce to [[Highest averages method|divisor methods]] which means that adding voters or winners will not change results in undesirable ways. The other three reduce to [[Largest remainder methods]] which obey Quota Rules but adding voters or winners may change outcomes in undesirable ways. One such way is failure of [[Participation criterion]]. It is not clear which is a fundamentally better choice since Quota Rules are inanimately tied with some definitions of proportionality.
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