Glossary of terms used in this report
Instant Runoff Voting (IRV): This is a voting system used to determine a majority winner in a single-seat race from a field of candidates. With IRV, each voter has one vote and ranks candidates in order of choice (1, 2, 3, etc.). All first choices are counted, and if no candidate wins a majority of first choices the retabulation of ballots simulates a series of run-off elections. The last place candidate (candidate with the least first-choices) is eliminated. Ballots of voters who ranked the eliminated candidate first are then redistributed to their second-choice candidates, as indicated on each voterís ballot. First-choice ballots for candidates still in the running are again counted for those favored candidates. Last place candidates are successively eliminated and ballots are redistributed to next choices until one candidate remains or a candidate gains over 50% of votes. IRV is not a system of proportional representation.
Plurality election rule: Under plurality elections, in a single-seat race, the candidate with the most votes wins even if that represents a minority of voters. With a field of five candidates, it is possible to win with as little as 21% of the vote, for example. Plurality winners may, or may not, be the most preferred-choice of a majority of the voters. For this reason, it is sometimes called "minority rule." Plurality election rules are common in the U.S.
Proportional Representation (PR): This refers to a variety of systems used for electing a legislature in which the number of seats a party wins is more or less proportional to the percentage of popular votes received. PR does NOT refer to a parliamentary system in which the executive branch of government is selected by the legislative branch. PR can be used to elect the legislature in either a parliamentary or a presidential system such as the United Statesí. PR is not part of this Commissionís recommendations.
Single Transferable Vote (STV): This is a preference voting system in which voters rank candidates in order of preference. The single vote can be transferred from one candidate to another according to the votersí rankings, depending on the cumulative result of other votersí ballots. STV can be used for IRV winner-take-all elections, and in multi-seat PR elections. In IRV elections, ballots can only be transferred from eliminated candidates to candidates still in the running. In PR elections, ballots can also be transferred from the surplus of a winning candidate, who has surpassed the winning threshold, to votersí alternate choices so as to minimize the number of wasted votes and achieve overall proportionality.
Winner-Take-All election: In contrast to PR, winner-take-all refers to an election rule whereby the majority (or in the case of plurality elections, merely the largest faction) in a district receives 100% of the seats. Some offices, such as Governor, are inherently winner-take-all, since there is only one seat. The vast majority of U.S. elections are currently winner-take-all. Winner-take-all systems tend to exclude minority voices from legislative debate.