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The participation criterion is a voting system criterion. It is also known as the "no show paradox". It has been defined〔(【引用サイトリンク】 author = Douglas Woodall )〕 as follows: * In a deterministic framework, the participation criterion says that the addition of a ballot, where candidate A is strictly preferred to candidate B, to an existing tally of votes should not change the winner from candidate A to candidate B. * In a probabilistic framework, the participation criterion says that the addition of a ballot, where each candidate of the set X is strictly preferred to each other candidate, to an existing tally of votes should not reduce the probability that the winner is chosen from the set X. Plurality voting, approval voting, range voting, and the Borda count all satisfy the participation criterion. All Condorcet methods,〔(【引用サイトリンク】title=Participation failure" is forced in Condorcet methods with at least 4 candidates )〕 Bucklin voting, and IRV〔(【引用サイトリンク】url=http://rangevoting.org/TBlecture.html#partic )〕 fail. Voting systems that fail the participation criterion allow a particularly unusual strategy of not voting to, in some circumstances, help a voter's preferred choice win. The participation criterion for voting systems is one example of a rational participation constraint for social choice mechanisms in general. == Quorum requirements == The most common failure of the participation criterion is not in the use of particular voting systems, but in simple yes or no measures that place quorum requirements. A public referendum, for example, if it required majority approval and a certain number of voters to participate in order to pass, would fail the participation criterion, as a minority of voters preferring the "no" option could cause the measure to fail by simply not voting rather than voting no. In other words, the addition of a "no" vote may make the measure more likely to pass. A referendum that required a minimum number of yes votes (not counting no votes), by contrast, would pass the participation criterion. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Participation criterion」の詳細全文を読む スポンサード リンク
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