Participation criterion
Criteria of voting system efficiency / From Wikipedia, the free encyclopedia
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The participation criterion, also called vote or population monotonicity, is a voting system criterion that says that a candidate should never lose an election as a result of having "too many supporters". It says that adding a voter who prefers Alice to Bob should not cause Alice to lose the election to Bob.[1]
Voting systems that fail the participation criterion exhibit the no-show paradox, where a voter is effectively disenfranchised by the electoral system (because turning out to vote would make a bad situation worse).[2] Such voting systems violate the principle of one man, one vote, as participation failures create situations where "one man has negative-one votes".
Positional and score voting methods satisfy the participation criterion. However, all methods satisfying paired majority-rule[3][4] can fail in and the highest median methods[5] can fail in some situations. Most notably, instant-runoff voting—a widely-used voting rule—fails the participation criterion.