Jump to content

Draft:Seat linkage mixed system

From Wikipedia, the free encyclopedia
Seat linkage compensatory systems, whether they use a single vote of two votes, take into account seats won by parties in the lower tier of the system.

[1][2][3]

A joint Politics and Economics series
Social choice and electoral systems
Single-winner methods
Single vote - plurality methods

Condorcet methods

Positional voting

Cardinal voting

Proportional representation
Party-list

Quota-remainder methods

Approval-based committees

Fractional social choice

Semi-proportional representation

Mixed systems
By results of combination
By mechanism of combination

By ballot type

Paradoxes and pathologies
Spoiler effects

Pathological response

Strategic voting

Paradoxes of majority rule

Social and collective choice
Impossibility theorems

Positive results

icon Mathematics portal

A seat linkage is a mechanism used in some mixed and proportional electoral systems in which seat won in one part (subsystem) of the electoral system are taken into account in the apportionment of the other seats. Seat linkage is a usually key element in achieving mixed-member proportional representation, but any system using leveling seats typically also relies on seat linkage.

Different compensatory seat linkage systems are sometimes conflated under the term mixed-member proportional representation (MMP), or (in the UK) additional member system. Seat linkage presumes the use of party lists, although these might be so open, that they work in the background "invisible" to the voter, such as the "best near-winner" model of MMP used in Baden-Württemberg.


Systems with seat linkage are further divided into compensatory and majority-assuring systems.[4]

Seat linkage is distinct from parallel voting, where there is no link between two subsystems (they are independent) and vote linkage, a different type of connection between two parts of the system.

Method for mixed-member proportional representation

[edit]

In typical seat linkage mixed systems, voters get two votes: one to elect the winner in single-seat constituency (usually by first-preference plurality), and another for the list of political party. Some seat linkage systems use a mixed single vote, which brings its own advantages and disadvantages.

Seats are first awarded to the successful constituency candidates, and then top-up seats and second, by party candidates based on the percentage of nationwide or region-wide votes that each party received.[5][6][7] party-list proportional representation.

MMP differs from parallel voting in that the nationwide seats are allocated to political parties

proportional election results across all seats (not just the additional seats).

two parties that each receive 25% of the votes end up with about 25% of the seats, even if one party wins more constituency seats than the other. Depending on the exact system implemented in a country and the results of a particular election, the proportionality of an election may vary.[8] Overhang seats may reduce the proportionality of the system, although this can be compensated for by allocating additional party list seats to cover any proportionality gap.[9]

Constituency seats only

(FPTP)

Mixed-member majoritarian Seat linkage compensation - broadly mixed-member proportional type of system (MMP)
Parallel voting

(supplementary member system)

Additional member system (AMS) Overhang seats re-added True MMP (with leveling seats)
Party Popular vote (%) Seats Share (%) Seats Share (%) Seats Share (%) Seats Share (%) Seats Share (%)
Party A 43% 54 77% 67 (54+13) 67% 54 (54+0) 54% 54 (54+0+0) 48% 71 (54+0+17) 43%
Party B 41% 11 16% 24 (11+13) 24% 34 (11+23) 34% 41 (11+23+7) 36% 68 (11+23+34) 41%
Party C 13% 0 0% 3 (0+3) 3% 7 (0+7) 7% 13 (0+7+6) 12% 21 (0+7+14) 13%
Party D 3% 5 7% 5 (5+0) 5% 5 (5+0) 5% 5 (5+0+0) 4% 5 (5+0+0) 3%
TOTAL 100% 70 100% 70+30 100% 70+30 100% 70+30+13 100% 70+30+65 100%
Index of disproportionality

(Gallagher)

31.55 (highly disproportional) 22.01 (disproportional) 10.25 (moderately disproportional) 4.97 (considered proportional) 0.25 (highly proportional)
Method used Only first-past-the-post 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 United Kingdom, among others Russia, among others Scotland, among others New Zealand formerly in Germany

Threshold

[edit]
See also: Election threshold

As in many systems containing or based upon party-list representation, in order to be eligible for list seats in some AMS models, a party must earn at least a certain percentage of the total party vote, or no candidates will be elected from the party list. Candidates having won a constituency will still have won their seat. In almost all elections in the UK there are no thresholds except the "effective threshold" inherent in the regional structure. However the elections for the London Assembly have a threshold of 5% which has at times denied seats to the Christian Peoples Alliance (in the 2000 election), the British National Party, Respect – The Unity Coalition (both in the 2004 election), and the Women's Equality Party (in the 2016 election).

Other names

[edit]

The seat linkage compensatory mixed system often referred to as MMP originates in Germany, and was later adopted with modifications under the name of MMP in New Zealand. In Germany, where is was differentiated from a different compensatory mixed system it was always known as personalized proportional representation (PPR) (German: personalisiertes Verhältniswahlrecht). Since the variants used in Germany almost always produce very proportional results, the proportionality is emphasized over the mixed nature of the electoral system, and it is essentially considered a localized or personalized form of PR, used instead of conventional open-list systems. The new modified federal election system does not allow overhang seats at all, therefore not all local districts are guaranteed to elect the plurality winner. In German, this localized list system now shares the name of PPR with the mixed systems still used in the federal states of Germany that are referred to as MMP in English. In English, due to this change, the system is no longer considered to be MMP in the sense of a mixed member system combining proportional and majoritarian representation, but it would be a personalized/localized version of PR. As it retains the individual candidate vote in a clearly distinct fashion from open-list systems, it may still be considered mixed-member proportional in the sense of a proportional system having two kinds of MP: one (may be) elected by personal (candidate) votes, one elected by (closed list) votes.

Previously, the federal elections used a flexible number of additional compensatory seats, also known as leveling seats, which essentially guaranteed mixed-member proportional representation even with extremely disproportional constituency results, but dramatically increased the size of the Bundestag. This meant that it was potentially the most proportional MMP system used after the one in New Zealand[citation needed], where only overhang seats are added back as list seats, which resulted in minor flexibility of the parliament size.

In the Canadian province of Quebec, where an MMP model was studied in 2007,[10] it is called the compensatory mixed-member voting system (système mixte avec compensation or SMAC). In the United Kingdom the sometimes less proportional implementation of seat linkage used in Scotland and the London Assembly is referred to as the additional member system.[11][12] 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.

As especially mixed electoral systems can be quite different, sometimes there is no consensus on their classification as mixed-member proportional, mixed majoritarian or something between the two. These cases include partially or conditionally compensatory systems such as those of Mexico and South Korea, which are typically said to be supermixed systems or partially compensatory systems, but sometimes inaccurately referred to as MMP even though they are highly disproportional.

Proportional variations

[edit]

Use

[edit]

Current

[edit]
Country Legislative body Use Number of votes (personal and list) Notes
Bolivia Bolivia Chamber of Deputies 1994–present Two votes Ballots use a double simultaneous vote with the presidential election[13]
Germany Germany Bundestag (lower house of the federal parliament) 1949–2023[14] Two votes Referred to as personalized proportional representation (see electoral system of Germany).[15] Came about in 1949 as a result of inter-party bargaining.[16] Originally used single vote version, switched to two vote version before the 1953 election. Levelling seats were established for the 2013 federal election after a ruling of Federal Constitutional Court, with a minor modification for the 2021 federal election to reduce the size of the Bundestag. The system was recently modified to an essentially (non-mixed) closed list proportional system with a local constituency vote (called personalized proportional representation) to eliminate the need for overhang seats. In the new system, the number of seats a party can win is capped, if they "won" more seats by plurality, not all of their winners will be elected.
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.
South Korea Republic of Korea (South Korea) 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.
Lesotho Lesotho 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.
New Zealand New Zealand House of Representatives 1994–present Two votes Following a long electoral reform process, beginning with the Royal Commission on the Electoral System in 1985 and ending with the 1993 referendum on the voting system. It was first used in an election in 1996. The system's use was reviewed by referendum in November 2011, with the majority (56.17%) voting to keep it. In 2020 general election, the Labour Party won 65 out of 120 seats, becoming the first party under MMP to receive a majority.
South Africa South Africa Local elections in all municipalities designated as metropolitan, district/county council (DC) or local/borough council(LC)[17] [citation needed] [citation needed] [citation needed]
United Kingdom United Kingdom Scotland Scotland - Scottish Parliament 1999–present Two votes[18] 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[18]

Former

[edit]
Country Legislative body Use Number of votes (personal and list) Notes
Albania Albania

(formerly)

Parliament (Kuvendi) 2001–2005 Two votes MMP was used from 2001 to 2005 (after having used parallel voting in the 1996 and 1997 elections).[19][20]
Germany Germany Bundestag (lower house of the federal parliament) 1949–2023[14] Two votes Referred to as personalized proportional representation (see electoral system of Germany).[15] Came about in 1949 as a result of inter-party bargaining.[16] Originally used single vote version, switched to two vote version before the 1953 election. Levelling seats were established for the 2013 federal election after a ruling of Federal Constitutional Court, with a minor modification for the 2021 federal election to reduce the size of the Bundestag. The system was recently modified to an essentially (non-mixed) closed list proportional system with a local constituency vote (called personalized proportional representation) to eliminate the need for overhang seats. In the new system, the number of seats a party can win is capped, if they "won" more seats by plurality, not all of their winners will be elected.
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.
Romania Romania (formerly) Chamber of Deputies 2008–2012 Single vote (MSV) Local candidates who did not win at least 50% of votes in their districts did not get a direct mandate, but these seats were added to the list seats allocated proportionally.

From the 2016 elections, closed party-list proportional representation was used instead.[21]

Thailand Thailand (formerly) House of Representatives 2019 Single vote (MSV) Referred to as "mixed-member apportionment", uses a mixed single vote for both the constituency and the party list. The 350 constituency seats are won by first-past-the-post voting as in previous elections. However, the 150 party-list seats serve a compensatory function, and are allocated so as to give each party a total number of seats proportional to the nationwide number of votes they received (top-up).[22][23][24][25] The next elections are again set to be held under parallel voting due to a change in the constitution.[26]
United Kingdom United Kingdom Wales Wales - Senedd (Welsh Parliament) 1999–2026 Two votes[18] In Wales, starting in 2026, the additional member system will be replaced by a closed-list proportional representation system following the approval of the Senedd Reform Bill.
Venezuela Venezuela (formerly) National Assembly ?–2009[citation needed] Two votes The link between list and constituency representatives was removed in 2009, which changed the system to parallel voting.[citation needed]

Tactical voting

[edit]

Decoy lists

[edit]

So-called "decoy lists" are a trick to unhinge the compensation mechanisms contained into the proportional part, so to de facto establish a parallel voting system.

For the 2020 South Korean legislative election the electoral system was changed and a partial use of AMS was implemented. In response, there were two satellite parties that only ran in the proportional part, the Future Korea Party (controlled by the United Future Party) and the Platform Party (controlled by the Democratic Party of Korea). Both merged with the parent party after the election.

Proposals, mixed ballots and hybrids

[edit]

Baden-Württemberg/Bavaria hybrid

A system using a mixed single vote in dual member districts (with local lists up to two candidates) called dual-member proportional has been proposed for Canada by Sean Graham.[27] DMP uses both vote transfer (within districts) and seat linkage.

An open list variant of MMP (modified Bavarian MMP) has been proposed by Jameson Quinn[28] which uses a mixed ballot and vote linkage combined with classical seat linkage.

  1. If a ballot supports the winner in the local district, the list part of that ballot is counted for the party of that local winner. (This is inspired by exhausting ballots in STV, and reduces the chances of "overhang".)
  2. If a ballot supports two different parties on its two halves, and exactly one of those two parties is nonviable (cannot win any seats), then it is counted as if both parts of that ballot supported the viable party. (This is inspired by transferring ballots in STV, and reduces the chances of "wasted/sub-threshold" voting power.

The vote linkage and seat linkage hybrid has been further refined by Markus Schulz[29], where in the proposed system uses STV on the local tier, and the votes for the local winner are only counted as votes for that candidate's party to the proportion as it is necessary to eliminate overhang seats. The proposal also contains a flexible number of leveling seats to ensure full proportionality.

See also

[edit]

References

[edit]
  1. ^ "Additional-member system: Politics". Encyclopædia Britannica. Retrieved 24 March 2016.
  2. ^ "Elections in Wales". Cardiff University. Archived from the original on 30 March 2016. Retrieved 25 March 2016.
  3. ^ "Electoral Reform and Voting Systems". Politics.co.uk. Archived from the original on 8 April 2020. Retrieved 25 March 2016.
  4. ^ https://core.ac.uk/download/pdf/39937848.pdf. {{cite web}}: Missing or empty |title= (help)
  5. ^ ACE Project Electoral Knowledge Network. "Mixed Member Proportional (MMP)". Retrieved 21 October 2017.
  6. ^ Shugart, Matthew; Wattenberg, Martin P. (2001). Mixed-Member Electoral Systems: Best of Both Worlds?. Oxford University Press. ISBN 9780191528972.
  7. ^ Bochsler, Daniel (May 13, 2010). "Chapter 5, How Party Systems Develop in Mixed Electoral Systems". Territory and Electoral Rules in Post-Communist Democracies. Palgrave Macmillan. ISBN 9780230281424.
  8. ^ Linhart, Eric; Raabe, Johannes; Statsch, Patrick (2018-03-01). "Mixed-member proportional electoral systems – the best of both worlds?". Journal of Elections, Public Opinion and Parties. 29 (1). Informa UK Limited: 21–40. doi:10.1080/17457289.2018.1443464. ISSN 1745-7289. S2CID 149188878.
  9. ^ Golosov, Grigorii V. (2013-10-01). "The Case for Mixed Single Vote Electoral Systems". The Journal of Social, Political, and Economic Studies. 38 (3). ISSN 0278-839X. Retrieved 2020-11-16.
  10. ^ "Characteristics of a compensatory mixed member voting system: Report of the Chief Electoral Officer" (PDF). Le Directeur général des élections du Québec. December 2007. Archived from the original (PDF) on 15 January 2018. Retrieved 24 October 2017.
  11. ^ "Electoral Reform and Voting Systems". Archived from the original on 8 April 2020. Retrieved 25 March 2016.
  12. ^ "Additional-member system: Politics". Encyclopædia Britannica. Retrieved 24 March 2016.
  13. ^ Mayorga 1997; Mayorga 2001, p. 194.
  14. ^ a b Schorkopf, Frank (2023-03-24). "Abschied von Adenauer oder weshalb die Wahlrechtsreform ein Verfassungsrechtsproblem ist". Verfassungsblog (in German). doi:10.17176/20230324-185228-0.
  15. ^ a b "The Voting System". BMI. Federal Ministry of the Interior, Building & Community.
  16. ^ a b Krennerich, Michael. "Germany: The Original Mixed Member Proportional System". ACE Project. The Electoral Knowledge Network.
  17. ^ "Election Types". Retrieved 9 September 2021.
  18. ^ a b c "Additional Member System". www.electoral-reform.org.uk. Retrieved 31 May 2024.
  19. ^ Gallagher 2011, p. 185; Gallagher 2014, p. 18.
  20. ^ Lublin, David. "Albania". Election Passport. American University. Retrieved 24 March 2016.
  21. ^ Filimon, Paul (20 July 2015). "Legea ALEGERILOR PARLAMENTARE pe LISTE, promulgată de Iohannis". România Liberă (in Romanian).
  22. ^ Bangkok Pundit (10 February 2016). "The effects of Thailand's proposed electoral system". Asian Correspondent. Archived from the original on 5 June 2019. Retrieved 24 March 2019.
  23. ^ Kendall, Dave (6 January 2019). "Explainer: New rules for the House of Representatives". Bangkok Post. Retrieved 24 March 2019.
  24. ^ Bangkok Pundit (10 February 2016). "The effects of Thailand's proposed electoral system". Asian Correspondent. Archived from the original on 5 June 2019. Retrieved 29 March 2019.
  25. ^ Kendall, Dave (6 January 2019). "Explainer: New rules for the House of Representatives". Bangkok Post. Retrieved 29 March 2019.
  26. ^ "With Eye to Next Election, Thai Government Tweaks Voting Rules".
  27. ^ Graham, Sean (April 4, 2016). Dual-Member Mixed Proportional: A New Electoral System for Canada (Report). University of Alberta. doi:10.7939/r3-qppp-b676.
  28. ^ "Bavarian MMP". electowiki. 2020-11-12. Retrieved 2024-09-03.
  29. ^ Schulze, Markus (2018). "The Schulze Method of Voting". arXiv:1804.02973 [cs.GT].
Retrieved from "https://en.wikipedia.org/w/index.php?title=Draft:Seat_linkage_mixed_system&oldid=1252426330"