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In proportional representation systems, an electoral quota is the number of votes a candidate needs to be guaranteed election. They are used in some systems where a formula other than plurality is used to allocate seats.
Generally quotas are set at a level that is guaranteed to apportion only as many seats as are available in the legislature. When the electorate is divided into separate districts, the quota is commonly set by reference to valid votes cast in the district.
The quota may be set at a number between: [1]
The smallest quota given above, votes/seats+1, is sometimes defended. Such a quota may be workable as long as rules are in place for dealing with situations where two or more tied candidates are competing for a lesser number of seats.
The common quotas used in single transferable voting elections are such that no more can achieve quota than the number of seats in the district.
There are two commonly-used quotas: the Hare and Droop quotas. The Hare quota is unbiased in the number of seats it hands out, and so is more proportional than the Droop quota (which tends to be biased towards larger parties); [2] [3]
However, the Hare sometimes does not allocate a majority of seats to a party with a majority of the votes. Droop quota guarantees that a party that wins a majority of votes in a district will win a majority of the seats in the district. [4] [5]
The Hare quota (also known as the simple quota or Hamilton's quota) is the most commonly-used quota for apportionments using the largest remainder method of party-list representation. It was used by Thomas Hare in his first proposals for STV. It is given by the expression:
Specifically, the Hare quota is unbiased in the number of seats it hands out. [2] It does suffer the disadvantage that it can allocate only a minority of seats to a party with a majority of votes. [6]
In at least one proportional representation system where the largest remainder method is used, the Hare quota has been manipulated by running candidates on many small lists, allowing each list to pick up a single remainder seat. [7] It is not clear that this is the fault of the Hare quota or in fact the election system that was used.
The Droop quota is used in most single transferable vote (STV) elections today and is occasionally used in elections held under the largest remainder method of party-list proportional representation (list PR). As well, it is identical to the Hagenbach-Bishoff quota, which is used to allocate seats by party in some list PR systems. [8]
The Droop quota is given by the expression: [1] [9]
It was first proposed in 1868 by the English lawyer and mathematician Henry Richmond Droop (1831–1884), who identified it as the minimum amount of support that would not possibly be achieved by too many compared to the number of seats in a district in semiproportional voting systems such as SNTV, leading him to propose it as an alternative to the Hare quota. [11]
While Hare quota makes it more difficult for a large party to take its full share of the seats, even denying a majority party a majority of seats, the Droop quota does not disadvantage larger parties. [12] Some say the Droop quota may go too far in that regard, saying it is the most-biased possible quota that can still be considered to be proportional. [1]
Today the Droop quota is used in almost all STV elections, including those in the Republic of Ireland, Malta, Australia, Northern Ireland, and India. [13]
In some implementations, a "uniform quota" is simply set by law – any candidate receiving that set number of votes is declared elected, with surplus transferred away.
Something like this system was used in New York City from 1937 to 1947, where seats were allocated to each borough based on voter turnout and then each candidate that surpassed set number of votes was declared elected, and enough others that came close to fill up the borough seats.
Under such a system, the number of representatives elected varied from election to election depending on voter turnout. Under NYC's STV, total seats on council varied: 1937 New York City Council election 26 seats, 1939 New York City Council election 21 seats, 1941 26 seats, 1943 17 seats, and 1945 23 seats. [14]
Like when Hare and Droop quotas are used, during the use of uniform quota, seats may be allocated to candidates who do not have full quota.
Proportional representation (PR) refers to any type of electoral system under which subgroups of an electorate are reflected proportionately in the elected body. The concept applies mainly to political divisions among voters. The essence of such systems is that all votes cast – or almost all votes cast – contribute to the result and are effectively used to help elect someone. Under other election systems, a bare plurality or a scant majority are all that are used to elect candidates. PR systems provide balanced representation to different factions, reflecting how votes are cast.
Party-list proportional representation (list-PR) is a system of proportional representation based on preregistered political parties, with each party being allocated a certain number of seats roughly proportional to their share of the vote.
The single transferable vote (STV) or proportional-ranked choice voting (P-RCV), is a multi-winner electoral system in which each voter casts a single vote in the form of a ranked ballot. Voters have the option to rank candidates, and their vote may be transferred according to alternative preferences if their preferred candidate is eliminated or elected with surplus votes, so that their vote is used to elect someone they prefer over others in the running. STV aims to approach proportional representation based on votes cast in the district where it is used, so that each vote is worth about the same as another.
In the study of electoral systems, the Droop quota is the minimum number of supporters a party or candidate needs to receive in a district to guarantee they will win at least one seat in a legislature.
The D'Hondt method, also called the Jefferson method or the greatest divisors method, is an apportionment method for allocating seats in parliaments among federal states, or in proportional representation among political parties. It belongs to the class of highest-averages methods. Compared to ideal proportional representation, the D'Hondt method reduces somewhat the political fragmentation for smaller electoral district sizes, where it favors larger political parties over small parties.
The Webster method, also called the Sainte-Laguë method, is a highest averages apportionment method for allocating seats in a parliament among federal states, or among parties in a party-list proportional representation system. The Sainte-Laguë method shows a more equal seats-to-votes ratio for different sized parties among apportionment methods.
The highest averages, divisor, or divide-and-round methods are a family of apportionment algorithms that aim to fairly divide a legislature between several groups, such as political parties or states. More generally, divisor methods can be used to round shares of a total, e.g. percentage points.
Victor Joseph Auguste D'Hondt was a Belgian lawyer and jurist of civil law at Ghent University. He devised a procedure, the D'Hondt method, which he first described in 1878, for allocating seats to candidates in party-list proportional representation elections. The method has been adopted by a number of countries, including Albania, Argentina, Armenia, Austria, Belgium, Bulgaria, Chile, Colombia, Croatia, Czech Republic, Denmark, Ecuador, Fiji, Finland, Israel, Japan, North Macedonia, the Netherlands, Northern Ireland, Paraguay, Poland, Portugal, Scotland, Slovenia, Serbia, Spain, Switzerland, Turkey, Iceland, Uruguay and Wales. A modified D'Hondt system is used for elections to the London Assembly and the Scottish Parliament.
The quota or divide-and-rank methods are a family of apportionment rules, i.e. algorithms for distributing seats in a legislative body between several groups. The quota methods begin by calculating an entitlement for each party, by dividing their vote totals by an electoral quota. Then, leftover seats are distributed by rounding up the apportionment for some parties. These rules are typically contrasted with the more popular highest averages methods.
The Imperiali quota or pseudoquota is an inadmissible electoral quota named after Belgian senator Pierre Imperiali. Some election laws have mandated it as the number of votes needed to be guaranteed to win earn a seat in single transferable vote or largest remainder elections.
In the study of apportionment, the Harequota is the number of voters represented by each legislator under an idealized system of proportional representation, where every legislator represents an equal number of voters and where every vote is used to elect someone. The Hare quota is the total number of votes divided by the number of seats to be filled. The Hare quota was used in the original proposal for a single transferable vote system, and is still occasionally used, although it has since been largely supplanted by the Droop quota.
The single transferable vote (STV) is a proportional representation system that elects multiple winners. It is one of several ways of choosing winners from ballots that rank candidates by preference. Under STV, an elector's vote is initially allocated to their first-ranked candidate. Candidates are elected (winners) if their vote tally reaches quota. After the winners in the first count are determined, if seats are still open, surplus votes — those in excess of an electoral quota— are transferred from winners to the remaining candidates (hopefuls) according to the surplus ballots' next usable back-up preference.
The Huntington–Hill method, sometimes called method of equal proportions, is a highest averages method for assigning seats in a legislature to political parties or states. Since 1941, this method has been used to apportion the 435 seats in the United States House of Representatives following the completion of each decennial census.
Proportionality for solid coalitions (PSC) is a criterion of proportionality for ranked voting systems. It is an adaptation of the quota rule to voting systems in which there are no official party lists, and voters can directly support candidates. The criterion was first proposed by the British philosopher and logician Michael Dummett.
Semi-proportional representation characterizes multi-winner electoral systems which allow representation of minorities, but are not intended to reflect the strength of the competing political forces in close proportion to the votes they receive. Semi-proportional voting systems are generally used as a compromise between complex and expensive but more-proportional systems and simple winner-take-all systems. Examples of semi-proportional systems include the single non-transferable vote, limited voting, and parallel voting.
An electoral or voting system is a set of rules used to determine the results of an election. Electoral systems are used in politics to elect governments, while non-political elections may take place in business, non-profit organisations and informal organisations. These rules govern all aspects of the voting process: when elections occur, who is allowed to vote, who can stand as a candidate, how ballots are marked and cast, how the ballots are counted, how votes translate into the election outcome, limits on campaign spending, and other factors that can affect the result. Political electoral systems are defined by constitutions and electoral laws, are typically conducted by election commissions, and can use multiple types of elections for different offices.
In mathematics and social choice, apportionment problems are a class of fair division problems where the goal is to divide (apportion) a whole number of identical goods fairly between multiple groups with different entitlements. The original example of an apportionment problem involves distributing seats in a legislature between different federal states or political parties. However, apportionment methods can be applied to other situations as well, including bankruptcy problems, inheritance law, manpower planning, and rounding percentages.
Seat bias is a property describing methods of apportionment. These are methods used to allocate seats in a parliament among federal states or among political parties. A method is biased if it systematically favors small parties over large parties, or vice versa. There are several mathematical measures of bias, which can disagree slightly, but all measures broadly agree that rules based on Droop's quota or Jefferson's method are strongly biased in favor of large parties, while rules based on Webster's method, Hill's method, or Hare's quota have low levels of bias, with the differences being sufficiently small that different definitions of bias produce different results.
Vote-ratio, weight-ratio, or population-ratio monotonicity is a property of some apportionment methods. It says that if the entitlement for grows at a faster rate than , should not lose a seat to . More formally, if the ratio of votes or populations increases, then should not lose a seat while gains a seat. An apportionment method violating this rule may encounter population paradoxes.
Static population-monotonicity, also called concordance, says that a party with more votes should not receive a smaller apportionment of seats. Failures of concordance are often called electoral inversions or majority reversals.