Part of the Politics and Economics series |
Electoral systems |
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Compensation or correction is an optional mechanism of electoral systems, which corrects the results of one part of the system based on some criterion to achieve a certain result, usually to make it more proportional. [1] There are in general two forms of compensation: vote linkage and seat linkage.
Compensation exists in many ranked voting systems such as instant-runoff voting and single transferable voting, where votes for eliminated candidates (and in the case of STV, surplus votes of elected candidates) are transferred to other candidates, thereby compensating voters who voted for candidates who may not be elected (or whose votes were not needed to get a candidate elected). This is an example of vote linkage compensation in a single-tier system. The equivalent of this type of compensation in case of party-list proportional representation is the spare vote.
In mixed electoral systems compensation is usually contrasted with superposition, which means two electoral systems are used independently of each other with multiple tiers. [2] Most mixed compensatory electoral systems use seat linkage (typically mixed-member proportional representation), however some use multi-tier vote linkage, which usually leads to less proportional results.
The two common ways compensation occurs are seat linkage compensation (or top-up) and vote linkage compensation (or vote transfer). [3] Like a non-compensatory mixed system, a compensatory mixed system may be based on the mixed single vote (voters vote for a local candidate and that vote is used to set the party share of the popular vote for the party that the candidate belongs to) or it may be based on voters casting two separate votes. [4]
In both mixed compensatory systems and mixed non-compensatory systems, two sets of seats are allocated using different methods. Most often, this involves one winner-take-all system, usually first-preference plurality. The remaining seats are allocated to political parties partially or wholly based on a proportional allocation method such as highest averages or largest remainder. The difference is whether or not the results of the district elections are considered when allocating the PR seats.[ citation needed ]
In mixed non-compensatory systems, such as parallel voting, the proportional allocation is performed independently of the district election component. [5]
In seat linkage mixed compensatory systems, the allocation of the top-up seats is done in such a way as to compensate as much as possible for dis-proportionality produced by the district elections. MMP generally produces proportional election outcomes, meaning that a political party that wins n percent of the vote will receive roughly n percent of the seats.[ citation needed ]
The following hypothetical example based on the one by Massicotte [5] illustrates how "top-up" PR seats are typically allocated in a compensatory system and in a non-compensatory system. The example assumes a 200-seat legislative assembly where 100 seats are filled using FPTP and the other 100 seats are awarded to parties using a form of PR. The table below gives the popular vote and FPTP results. The number of PR seats allocated to each party depends on whether the system is compensatory or non-compensatory.[ citation needed ]
Party | Popular vote | FPTP seats | PR seats | Total seats (FPTP + PR) | FPTP seats | |
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Party A | 44% | 64 | ? | ? | ![]() | |
Party B | 40% | 33 | ? | ? | ||
Party C | 10% | 0 | ? | ? | ||
Party D | 6% | 3 | ? | ? | ||
TOTAL | 100% | 100 | 100 | 200 |
In non compensatory system, each party wins its proportional share of the 100 PR seats. Under such a system, the total number of seats (FPTP + PR) received by each party would not be proportional to its share of the popular vote. Party A receives just slightly less of the popular vote than Party B, but receives significantly more seats. In addition to its success in the district contests, Party A receives almost as many of the PR seats as Party B.
If the PR seats are allocated in a compensatory system, the total number of seats awarded to each party is proportional to the party's share of the popular vote. Party B wins 33 of the district seats and its proportional share of the 200 seats being filled is 80 seats (40 percent of the total 200 seats) (the same as its share of the popular vote) so it is awarded 47 of the PR seats.
In practice, compensatory seat allocation is complicated by the possibility that one or more parties wins so many of the district seats ("overhang") that the available number of PR seats is insufficient to produce a fully proportional outcome. [3] Some mixed compensatory systems have rules that address these situations by adding additional PR seats to achieve overall PR. These seats are used only until the next election, unless needed again at that time. [5]
In MMP, the voter casts two votes: one for a constituency representative and one for a party. In the original variant used in Germany, citizens gave only one vote, so that voting for a representative automatically meant also voting for the representative's party, which is still used in some MMP elections today and is more robust against tactical voting than typical two-vote versions. Most of Germany changed to the two-vote variant to make local members of parliament (MPs) more personally accountable. Voters can thus vote for the local person they prefer for local MP without regard for party affiliation, since the partisan make-up of the legislature is determined only by the party vote. In the 2017 New Zealand election, 27.33% of voters split their vote (voted for a local candidate of a different party than their party vote) compared to 31.64% in 2014. [6]
The Scandinavian countries have a long history of using both multi-member districts (members elected through party-list PR) and nationally based compensatory top-up seats using the same method as MMP, however because the local MPs are also elected using PR, these systems are not usually considered MMP as they are not mixed systems.
When a party wins more constituency seats than it would be entitled to from its proportion of (party list) votes, most systems allow for these overhang seats to be kept by those candidates who earned it in the constituency elections. A counter-example would be the MMP variant used in Romania in the 2008 and 2012 legislative elections, where constituency seats could only be earned by the winning candidate if they also achieved an absolute majority in their district, thereby eliminating overhang seats.[ citation needed ]
In Germany's Bundestag and the New Zealand House of Representatives, all members elected for constituencies keep their seats. For example, in the 2008 New Zealand general election the Māori Party won 2.4% of the party vote, which would entitle them to 3 seats in the House, but won 5 constituency seats, leaving an overhang of 2 seats, which resulted in a 122-member house. If the party vote for the Māori Party had been more in proportion with the constituency seats won, there would have been a normal 120-member house.[ citation needed ]
In most German states, and in the federal Bundestag since 2013, the other parties receive extra seats (leveling seats) to create full proportionality. For example, the provincial parliament ( Landtag ) of North Rhine Westphalia has, instead of the usual 50% compensatory seats, only 29% unless more are needed to balance overhangs. If a party wins more local seats than its proportion of the total vote justifies, the size of the Landtag increases so that the total outcome is fully proportional to the votes, with other parties receiving additional list seats to achieve proportionality. The leveling seats are added to the normal number of seats for the duration of the electoral period. In the German state of Bavaria, the constituency vote and party vote are combined to determine the distribution of seats.[ citation needed ]
Scotland and Wales use a modified variant of MMP known as the additional-member system where due to the nature of the calculations used to distribute the regional list seats, overhang seats are not possible; the list allocation works like a mixed-member majoritarian system, but in using the d'Hondt method's divisors to find the averages for the allocation, the first divisor for each party takes into account the number of constituency seats won by the party; i.e. a party that won 7 constituency seats would start with a divisor of 8 (7 seats + 1 per the method's divisor formula) instead of 1. The resulting table would then give 7 seats for Scotland and 4 seats for Wales to the parties possessing the highest averages on the table, although both devolved parliaments do not use a table, instead using a sequential method. The compensatory effect characteristic of MMP is in the fact that a party that won constituency seats would have lower averages on the table than it would if the election used MMM. Because of no provision for overhang seats, there have been cases where a party ended up with fewer total seats than its proportional entitlement. This occurred, for example, in the elections in the South East Wales electoral region in both 2007 (Welsh Conservatives under-represented) and in 2016 (Welsh Labour over-represented, Plaid Cymru under-represented). Labour has also been over-represented on this basis in every election in the South Wales West region, and every election in the South Wales Central region apart from the 2003 election. This situation arises because Labour has continued to hold the overwhelming majority of constituency seats in these regions, and only around one-third of the total number of seats are available for distribution as additional regional seats.[ citation needed ]
Parallel voting (MMM) | Broadly mixed-member proportional type of system (MMP) | |||||||||
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Additional member system (AMS) | Overhang seats re-added | True MMP (with leveling seats) | ||||||||
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Party | Popular vote (%) | Seats | Share (%) | Seats | Share (%) | Seats | Share (%) | Seats | Share (%) | |
Party A | 43% | 67 (54+13) | 67% | 54 (54+0) | 54% | 54 (54+0+0) | 48% | 71 (54+0+17) | 43% | |
Party B | 41% | 24 (11+13) | 24% | 34 (11+23) | 34% | 41 (11+23+7) | 36% | 68 (11+23+34) | 41% | |
Party C | 13% | 3 (0+3) | 3% | 7 (0+7) | 7% | 13 (0+7+6) | 12% | 21 (0+7+14) | 13% | |
Party D | 3% | 5 (5+0) | 5% | 5 (5+0) | 5% | 5 (5+0+0) | 4% | 5 (5+0+0) | 3% | |
TOTAL | 100% | 70+30 | 100% | 70+30 | 100% | 70+30+13 | 100% | 70+30+65 | 100% | |
Index of disproportionality | 22.01 (disproportional) | 10.25 (moderately disproportional) | 4.97 (considered proportional) | 0.25 (highly proportional) | ||||||
Method used | Independent PR tier | Fixed number of compensatory seats | Number of (extra) leveling seats = number of overhang seats | As many leveling seats as needed | ||||||
This type of system used in | Russia, among others | Scotland, among others | New Zealand | formerly in Germany |
Some compensatory electoral systems have properties that make them vulnerable to manipulation, which is usually intended to subvert the compensation mechanism.[ citation needed ]
Compensatory mixed systems | ||
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single vote systems | dual vote systems | |
Seat linkage | mixed single vote, top-up versions (MSV)
| mixed-member proportional representation (MMP) |
additional member system (AMS) | ||
alternative vote plus (AV+) | ||
Hybrids: e.g. parallel voting+AMS (South Korea) | ||
Vote linkage | positive vote transfer (PVT/MSV)
| Hybrids:
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Others systems: | ||
dual-member proportional (DMP) | mixed ballot transferable vote (MBTV) |
MMP and AMS have a tier of district representatives typically elected by FPTP, and a tier of regional or at-large representatives elected by PR. Unlike in parallel voting, the PR seats are allocated in a manner that corrects disproportionality caused by the district tier. MMP corrects disproportionalities by adding even more leveling seats, this system is used by New Zealand.[ citation needed ]
The type of MMP which does not always yield proportional results, but sometimes only "mixed semi-proportional representation" is called an additional member system. If the fixed number of compensatory seats are enough to compensate the results of the majoritarian FPTP/SMP side of the election, AMS is equivalent to MMP, but if not, AMS does not compensate for remaining overhang seats. In Bolivia and Lesotho, where single vote versions of AMS are used with a relatively large number of compensatory seats, results are usually proportional. AMS models used in parts of the UK (Scotland and Wales), with small regions with a fixed number of seats tend to produce only moderately proportional election outcomes.[ citation needed ]
While the (very similar) majority bonus systems are considered non-compensatory, majority jackpot systems technically assign the seats outside the jackpot without including the party that received the jackpot, therefore are compensatory in that sense. Some systems, like the one in Armenia, also includes a minority jackpot.[ citation needed ]
Scorporo is a two-tier mixed system similar to MMP in that voters have two votes (one for a local candidate on the lower tier, and one for a party list on the upper tier), except that disproportionality caused by the single-member district tier is partially addressed through a vote transfer mechanism. [7] Votes that are crucial to the election of district-winning candidates are excluded from the PR seat allocation, for this reason the method used by scorporo is referred to as a negative vote transfer system. [8] The system was used in Italy from 1993 to 2005, and a modified version is currently used in Hungary. [9]
MBTV is a mixed compensatory type of systems similar to MSV, except voters can vote separately for a local candidate and as a transfer vote on the compensatory tier. [10] It is different from MMP/AMS and AV+ in that there is a vote linkage (instead of seat linkage) between the tiers. The two parts of the dual ballot are tied in a way that only those lists votes get counted, which are on ballots that would be transfer votes in an equivalent positive vote transfer MSV system.[ citation needed ]
AV+ is a mixed compensatory system similar to the additional member system, with the notable difference that the district seats are awarded using the alternative vote. The system was proposed by the Jenkins Commission as a possible alternative to FPTP for elections to the Parliament of the United Kingdom.[ citation needed ]
DMP is a mixed compensatory system similar to MMP, except that the plurality and PR seats are paired and dedicated to dual-member (two seat) districts. Proposed as an alternative to FPTP for Canadian elections, DMP appeared as an option on a 2016 plebiscite in Prince Edward Island and a 2018 referendum in British Columbia.[ citation needed ]
Country | Legislative body | Use | Number of votes (personal and list) | Notes |
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Armenia | ||||
![]() | Chamber of Deputies | 1994–present | Two votes | |
![]() | State parliaments, except | varies by state | varies by state | Bavaria uniquely uses an open-list system for its party-list seats. Baden-Württemberg uses MMP without lists. |
Hungary | ||||
![]() | National Assembly | 2019–present | Two votes | Originally used a hybrid system with 253 single-member constituency seats, 17 supplementary seats (a la parallel voting) and 30 compensatory seats elected using the additional-member system variant of MMP. Now uses a straightforward AMS system with all proportional seats being compensatory since 2024. |
![]() | National Assembly | 2002–present | Single vote (MSV) | Initially used two vote version, changed to the single vote version in 2012 due to the use of decoy lists. |
Mexico | ||||
![]() | House of Representatives | 1994–present | Two votes | |
![]() | ![]() | 1999–present | Two votes [11] | Modified version of MMP referred to as the additional-member system, which in Scotland is divided into regions. |
Local elections in | 2000–present | Two votes [11] |
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. Further, a PR system is one that produces mixed and balanced representation, 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 additional-member system (AMS) or is a mixed electoral system under which most representatives are elected in single-member districts (SMDs), and a fixed number of other "additional members" are elected to make the seat distribution in the chamber more proportional to the way votes are cast for party lists. It is distinct from parallel voting in that the "additional member" seats are awarded to parties taking into account seats won in SMDs, which is not done under parallel voting.
Mixed-member proportional representation is a mixed electoral system which combines local winner-take-all elections with a compensatory tier of party list votes, which are used to allocate additional members in a way that aims to produce proportional representation overall. In typical MMP systems, voters get two votes: one to decide the representative for their single-seat constituency, and one for a political party. Some countries use single vote variants of MMP, although this article focuses primarily on dual vote versions of MMP.
Overhang seats are constituency seats won in an election under the traditional mixed-member proportional (MMP) system, when a party's share of the nationwide votes would entitle it to fewer seats than the number of individual constituencies won. The electoral reform in Germany removed the overhang seats, and replaced with Zweitstimmendeckung.
First-preference plurality (FPP)—often shortened simply to plurality—is a single-winner system of positional voting where voters mark one candidate as their favorite, and the candidate with the largest number of points is elected. It is also called first-past-the-post (FPTP), based on a metaphor from horse racing.
In political science, parallelvoting or superposition refers to the use of two or more electoral systems to elect different members of a legislature. More precisely, an electoral system is a superposition if it is a mixture of at least two tiers, which do not interact with each other in any way; one part of a legislature is elected using one method, while another part is elected using a different method, with all voters participating in both. Thus, the final results can be found by calculating the results for each system separately based on the votes alone, then adding them together. A system is called fusion or majority bonus, another independent mixture of two system but without two tiers. Superposition is also not the same as "coexistence", which when different districts in the same election use different systems. Superposition, fusion and coexistence are distinct from dependent mixed electoral systems like compensatory (corrective) and conditional systems.
A referendum was held on October 10, 2007, on the question of whether to establish a mixed member proportional representation (MMP) system for elections to the Legislative Assembly of Ontario. The vote was strongly in favour of the existing plurality voting or first-past-the-post (FPTP) system.
A party-list system is a type of electoral system that formally involves political parties in the electoral process, usually to facilitate multi-winner elections. In party-list systems, parties put forward a list of candidates, the party-list who stand for election on one ticket. Voters can usually vote directly for the party-list, but in other systems voters may vote for directly individuals candidates within or across party lists, besides or instead of voting directly for parties.
Scotland uses different electoral systems for elections to Parliament, the Scottish Parliament and to local councils. A different system was also in use between 1999 and 2019 for United Kingdom elections to the European Parliament. Historically, only First Past the Post (FPTP) was used for all elections in Scotland, but this changed in 1999 both with the introduction of D'Hondt elections to the EU Parliament and the inception the same year of the devolved Scottish Parliament. Two of the devolved legislatures in the United Kingdom - the Scottish Parliament and the Senedd - use the Additional Members System (AMS). AMS has been used for every Scottish Parliament election since 1999, with the most recent being in 2021.
Electoral reform is a change in electoral systems which alters how public desires are expressed in election results.
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 that determine how elections and referendums are conducted and how their results are determined. 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.
Scorporo is a partially compensatory, mixed-member majoritarian electoral system, sometimes referred to as a negative vote transfer system (NVT) whereby a portion of members are elected in single-member districts (SMDs) and a portion are elected from a list. It may be fully defined as a parallel voting system which excludes a portion of the SMD winners' votes in electing the proportional tier, to result in a more proportional outcome. The exclusion of a portion of the SMD winners' votes is what makes scorporo fundamentally different from parallel voting and somewhat closer to mixed-member proportional representation in theory. However, the design proved susceptible to the decoy list strategy, and as a result by 2001 had devolved into a de facto parallel voting system. The method is only known to have been used in Italy and for a portion of the compensatory tier of the National Assembly of Hungary.
Dual-member proportional representation (DMP), also known as dual-member mixed proportional, is an electoral system designed to produce proportional election results across a region by electing two representatives in each of the region’s districts. The first seat in every district is awarded to the candidate who receives the most votes, similar to first-past-the-post voting (FPTP). The second seat is awarded to one of the remaining district candidates so that proportionality is achieved across the region, using a calculation that aims to award parties their seats in the districts where they had their strongest performances.
A mixed electoral system or mixed-member electoral system combines methods of majoritarian and proportional representation (PR). The majoritarian component is usually first-past-the-post voting (FPTP/SMP), whereas the proportional component is most often based on party-list PR. The results of the combination may be mixed-member proportional (MMP), where the overall results of the elections are proportional, or mixed-member majoritarian, in which case the overall results are semi-proportional, retaining disproportionalities from the majoritarian component.
Rural–urban proportional representation (RUP), also called flexible district PR, is a mixed electoral system which combines the use of single- and multi-member constituencies in a lower tier and top-up seats in an upper tier to meet the different needs of both rural and urban areas, while protecting the objective of proportionality. The term was coined by Fair Vote Canada, which devised a rural–urban system with the intention of meeting the special challenges of Canada's geography, which includes wide-flung, sparsely populated areas.
The mixed single vote (MSV) or positive vote transfer system (PVT) is a mixed-member electoral system, where voters cast a single vote in an election, which used both for electing a local candidate and as a vote for a party affiliated with that candidate according to the rules of the electoral system. Unlike the more widespread mixed proportional and mixed majoritarian systems where voters cast two votes, split-ticket voting is not possible in MSV.
The mixed ballot transferable vote (MBTV) refers to a type of vote linkage-based mixed-member electoral system where a group of members are elected on local (lower) tier, for example in single-member districts (SMDs). Other members are elected on a compensatory national (upper) tier from a list and voters cast a single ballot where they may indicate their preferences separately.
Mixed-member majoritarian representation (MMM) is type of a mixed electoral system combining winner-take-all and proportional methods, where the disproportional results of the winner-take-all part are dominant over the proportional component. Mixed member majoritarian systems are therefore categorized under semi-proportional representation, and are usually contrasted with mixed-member proportional representation (MMP) which aims to provide proportional representation compensation ("top-up") seats.