47 articles
Ostrogorski's paradox
Ostrogorski's paradox is a social choice result from Ostrogorski's 1902 Democracy and the Organization of Political Parties: voting by party platform, the party losing every issue can win the election, as in the 5-voter, 3-issue example.
Participation criterion
Participation criterion: a social choice theory axiom requiring that adding voters who prefer candidate x to y cannot change the winner from x to y; linked to the no show paradox and Moulin's 1988 impossibility theorem.
Plurality block voting
Plurality block voting (block vote, plurality-at-large voting): a multi-member plurality system where each voter casts as many votes as seats and the top n candidates win; used in Mauritius, Brazil, Iran, and the Philippines.
Quota rule
Quota rule: apportionment fairness criterion requiring each state or party to receive seats between its lower and upper quota. Hamilton's method satisfies it; Jefferson, Adams, Webster, and Huntington-Hill can violate it; Balinski-Young theorem limits combinations.
Rasmussen Reports
Rasmussen Reports, an American polling firm founded in 2003 by Scott Rasmussen, uses automated surveys and party weighting; known for a Republican-leaning bias, its daily Presidential Tracking Poll, and its 2024 removal from FiveThirtyEight averages.
Social choice theory
Social choice theory studies procedures aggregating individual votes, preferences, judgments, or welfare into collective decisions. Key results include Condorcet's paradox, Arrow's impossibility theorem, the Gibbard-Satterthwaite theorem, and May's characterization of majority rule.
Spoiler effect
Spoiler effect: a losing candidate changes an election's outcome by splitting votes with a similar candidate, also called vote splitting or the Nader effect. Plurality voting is most vulnerable; ranked, approval, and Condorcet methods reduce it differently.
State-population monotonicity
State-population monotonicity: apportionment axiom barring a growing state from losing a seat to a shrinking one (population paradox). Divisor methods satisfy it; Balinski-Young shows quota and this monotonicity are incompatible.
Strategic voting
Strategic (tactical) voting: casting a ballot for a second-preferred candidate or party because it has a better chance of winning; distinct from sincere voting, measured via surveys, and unavoidable under Gibbard-Satterthwaite.
Supermajority
Supermajority: a voting threshold above simple majority (three-fifths, two-thirds, three-fourths) for constitutional amendment, treaties, vetoes, and referendums; distinct from the filibuster's de facto Senate 60-vote rule.
Swing (politics)
Electoral swing measures the change in party vote share between elections, typically the Butler two-party average in percentage points. Invented by David Butler (1947) and popularized by the BBC Swingometer (1955, 1959), it underpins uniform national swing seat projections and swing voter analysis.
Three-fifths Compromise
The Three-fifths Compromise (1787) counted three fifths of each state's enslaved population, also called the federal ratio, for House apportionment and direct taxes under Article I, Section 2; superseded by the Fourteenth Amendment.
United States census
The United States census is the constitutionally mandated once-a-decade population and housing count run by the Census Bureau since 1790 for House apportionment and federal funding distribution.
United States congressional apportionment
United States congressional apportionment distributes the 435 House seats among the 50 states after each decennial census using the Method of Equal Proportions, adopted in 1941, based on each state's apportionment population; DC and Puerto Rico are excluded.
United States presidential approval rating
A United States presidential approval rating measures the share of Americans who approve of the sitting president's job performance, with Gallup's series running since 1938 and peaks like George W. Bush's 90% after September 2001.
Vote splitting
Vote splitting, also called the spoiler effect, occurs when similar candidates divide the same voter pool, letting a rival win under plurality rules. Ranked-choice and Condorcet methods reduce but do not eliminate it; proportional systems show related spoiler types.
Voting paradoxes: overview and catalog
Voting paradoxes are named failures of voting rules that violate obvious fairness properties, such as a candidate losing after gaining support, cataloged since Condorcet's 1785 cycle.