Given possible confusion with terminology, we recommend reading the glossary.
Additional Member System -Another term for a mixed member proportional system.
Alternative Vote (AV) - A preferential, plurality-majority system used in single-member districts in which voters use numbers to mark their preferences on the ballot paper. A candidate who receives over 50% of first-preferences is declared elected. If no candidate achieves an absolute majority of first-preferences, votes are re-allocated unfit one candidate has an absolute majority of votes cast
Apparentement - A device used in some list proportional representation systems which enables separate parties to declare themselves linked for the purpose of seat allocation.
Ballot structure - The way in which electoral choices are presented on the ballot paper. Ballots can be either ordinal or categorical.
Bi-cameral Parliament - A legislature comprised of two houses, usually known as an upper house and a lower house.
Block Vote - A plurality-majority system used in multi-member districts in which electors have as many votes as there are candidates to be elected. Voting can be either candidate-centered or party-centered. Counting is identical to a First Past the Post system, with the candidates with the highest vote totals winning the seats. Also known as or Bloc Vote.
Candidate-centered Ballot - A form of ballot in which an elector chooses between candidates.
Categorical Ballot - A form of ballot in which only a single choice for a candidate or party can be made.
Choice voting - The single transferable vote form of proportional representation, in which voters rank candidates in order of choice, all candidates who reach the threshold are elected, surplus votes are distributed to voters' next choices, and the candidates with the fewest votes are successively eliminated until all seats are filled.
Closed List - A form of list proportional representation in which electors are restricted to voting for a party only, and cannot express a preference for any candidate within a party list.
Communal Roll - A register of voters in which ascriptive criteria such as race or ethnicity determine which electors can enroll to vote, and which candidates can be elected, within the wider electoral contest.
Compensatory Seats - The list PR seats in a mixed member proportional system which are awarded to parties on the basis of their proportion of the national vote and designed to correct any disproportionality in the results of the elections held in plurality-majority district seats.
Constituency - A synonym for district, used predominantly in Anglophone countries outside of the United States.
Contiguous districts - Districts comprised of areas which are geographically adjoined or touching.
Cross Cutting Cleavages - Political allegiances of voters which cut across societal cleavages of ethnicity, religion, or class.
Cumulative Vote - The capacity of voters within some voting systems to cast more than one vote for a favored candidate.
d'Hondt Formula - One way of working out list PR results by the highest average method. Uses divisors of 1,2,3,4, etc.
Democratic Consolidation - The process by which a nation's political institutions and democratic procedures become legitimized and broadly accepted by both political actors and the wider population.
Distribution Requirements - The requirement that to win election a candidate must not merely win a specified proportion of the vote nationally but also a specified degree of support from different regions.
District - Geographic areas into which a country is divided for electoral purposes. Districts may return one member to parliaments or more than one.
District Magnitude - The number of members to be elected in each district.
Droop Quota - Used in highest average list PR and STV electoral systems to determine how seats are awarded. The quota is ascertained by the following formula: total vote divided by the number of seats plus one, then one is added to the product.
Electoral Formula - That part of the electoral system dealing specifically with the translation of votes into seats.
Electoral Law - The constitutional and legal provisions governing all aspects of the electoral process.
Electoral System - That part of the electoral rules which determines electoral outcomes; chiefly, the electoral formula, the ballot structure, and district magnitude.
First Past the Post (FPTP) - The simplest form of plurality-majority electoral system, -single-member districts, a categorical ballot and candidate-centered voting. The winning candidate is the one who gains more votes than any other candidate, but not necessarily a majority of votes.
Free List - A form of list proportional representation which provides for apparentement or cumulative voting.
Full Representation (PR) - Any system which consciously attempts to reduce the disparity between a party's share of the national vote and its share of the parliamentary seats. For example, if a party wins 40 per cent of the votes, it should win approximately 40 per cent of the seats.
Gerrymandering - The deliberate manipulation of district boundaries so as to advantage or disadvantage a particular interest.
Hagenbach-Bischoff Formula - Another term for the Droop Quota.
Hare Quota - Used in largest remainder PR electoral systems to determine how seats are awarded. The quota is ascertained by the following formula: total vote divided by the number of seats.
Heterogeneous - Diverse and/or inter-mixed.
Highest Average Method - A formula used with list PR systems to translate votes into seats. Party vote totals are divided by a series of devisors, under d'Hondt (by 1,2,3, etc.) or Sainte-Lagu╬ by 1,3,5, etc.) formula. After each stage the party with the highest average wins the seat. The count continues with party vote totals being divided by sequential numbers until all seats are filled.
Homogeneous - Similar and/or uniform.
Imperiali Quota - Sometimes used in largest remainder PR electoral systems to determine how seats are awarded. The quota is ascertained by the following formula: total vote divided by the number of seats plus two.
Index of Disproportionality - A figure which illustrates the collective disparity between the votes cast for parties in an election and the seats in parliament they win.
Invalid Votes - Ballots which, due to accidental or deliberate errors of marking on the part of voters, are unable to be included in the count.
IRV (Instant Runoff Voting)- Instant runoff voting is a winner-take-all, constitutionally protected, voting system that ensures a winning candidate will receive an absolute majority of votes rather than a simple plurality. IRV eliminates the need for runoff elections by allowing voters to rank their candidates in order of preference.
Largest Remainder Method - The Hare, Droop and Imperiali calculation methods which translate votes into seats within list PR systems. There are two stages to the count. First, parties are awarded seats in proportion to the number of quotas they fulfill (quotas vary depending on which of the three systems are used). Second, remaining seats are awarded to parties on the basis of the left over votes they possess after the 'quota' stage of the count. Largest remainder seats are allocated in order of vote size.
Lemas - A form of apparentement used predominantly in Latin America.
Limited Vote - A plurality-majority system used in multi-member district in which electors have more than one vote but fewer votes than there are candidates to be elected. Counting is identical to a first past the post system, with the candidates with the highest vote totals winning the seats.
List Proportional Representation (List PR) - In its most simple form List PR involves each party presenting a list of candidates to the electorate, voters vote for a party, and parties receive seats in proportion to their overall share of the national vote. Winning candidates are taken from the lists. Lists can be open, closed, or free.
Lower House - The first, and usually most important, chamber in a bicameral parliament.
Malapportionment - The uneven distribution of voters between electoral districts.
Majority-Plurality (Two-Round System) - In French Two-Round elections any candidate who has received the votes of over 12.5 per cent of the registered electorate in the first round can stand in the second round. Whoever wins the highest numbers of votes in the second round is then declared aimed, regardless of whether they have won an absolute majority or not. We therefore refer to it as majority-plurality variant of the two-round system.
Majority-Runoff (Two-Round System) - The most common method for the second round of voting in a Two-Round System is a straight 'run-off" contest between the two highest vote-winners from the first round - this we term a majority-runoff system.
Manufactured Majority - Where a single party wins less than 50 per cent of the valid votes, but an absolute majority of the parliamentary seats.
Mixed Member Proportional (MMP) - Systems in which a proportion of the parliament (usually half is elected from plurality-majority districts, while the remaining members are chosen from PR lists. Under MMP the list PR seats compensate for any disproportionality produced by the district seat results.
Multi-Member District - A district from which more than one member is elected to parliament.
Open List - A form of list proportional representation in which electors can express a preference for a candidate within a party list, as well as voting for the party.
Ordinal Ballot - A form of ballot in which a voter's choice can be rank-ordered (as for full representation systems), changed between one round of voting and the next (as for two- round systems) or split between two or more parties or candidates (as for Block and panachage list PR systems).
Panachage - A device used in some list proportional representation systems which enables an elector to vote for more than one candidate across different party lists.
Parallel System - A semi- proportional system in which full representation is used in conjunction with a plurality-majority system but where, unlike MMP, the PR seats do not compensate for any disproportionality arising from elections to the plurality- majority seats.
Party Block Vote (PB) - A form of the Block Vote in which electors choose between parties rather than candidates. The successful party will typically win every seat in the district.
Party-centered Ballot - A form of ballot in which an elector chooses between parties.
Plurality-Majority Systems - The distinguishing feature of plurality-majority systems is that they almost always use single-member districts. In a first past the post system, the winner is the candidate with a plurality of votes, but not necessarily an absolute majority of the votes. When this system is used in multi-member districts it becomes the block vote. Majority systems, such as the Australian Alternative Vote and the French two-round system, try to ensure that the winning candidate receives an absolute majority of votes cast.
PR (Proportional Representation)- See Full Representaion.
Preferential Voting - Electoral systems in which voters can rank-order candidates on the ballot paper in order of their choice. The Alternative Vote, the Single Transferable Vote and the system used to elect the Sri Lankan president are all examples of preferential voting. We prefer the term, choice voting, for the proportional form of preferential voting, which is also referred to the single transferable vote (STV).
Quota - The threshold for winning a seat in full representation systems.
Regional Fiefdom - A situation in which one party wins all, or nearly all, of the seats in a particular geographic region.
Reserved Seats - Seats in which some ascriptive criteria such as religion, ethnicity, language, gender etc. is a requirement for election.
Sainte-Lagu╬ Formula - One way of working out list PR results by the highest average method. Uses divisors of 1,3,5,7, etc.
Semi-Proportional Systems (Semi-PR) - Those electoral systems which provide, on average, results which fall some way in between the proportionality of PR systems and the disproportionality of plurality-majority systems.
Single-Member District - A district from which only one member is elected to parliament.
Single Non-Transferable Vote (SNTV) - A semi-proportional system which combines multi-member district with a first past the post method of vote counting, and in which electors have only one vote.
Single Transferable Vote (STV) - The choice voting form of proportional representation. It is a preferential proportional representation system used in multi-member districts. To gain election, candidates must surpass a specified quota of first-preference votes. Voters' preferences are re-allocated to other continuing candidates when an unsuccessful candidate is excluded or if an elected candidate has a surplus.
Threshold - The minimum level of support which a party needs to gain representation; usually expressed as a percentage of the total vote.
Two-Tier Districting - Where seats are awarded to parties from both single member districts and national PR lists, or both regional and national PR lists.
Two-Round System (TRS) - A plurality-majority system in which a second election is held if no candidate achieves an absolute majority of votes in the first election.
Upper House - The second, and usually less important chamber of a bicameral parliament .
Wasted Votes - Those votes which did not ultimately count towards the election of a particular candidate or party.