Social:List of electoral systems

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An electoral system (or voting system) is a set of rules that determine how elections and referendums are conducted and how their results are determined.

Some electoral systems elect a single winner (single candidate or option), while others elect multiple winners, such as members of parliament or boards of directors.

The study of formally defined electoral methods is called social choice theory or voting theory, and this study can take place within the field of political science, economics, or mathematics, and specifically within the subfields of game theory and mechanism design.

List of electoral systems by types

Key

  • Name (abbr.) and other names of the system (other names that may sometimes refer to other systems)
  • Type of representation: the most common division of electoral systems
  • Mixed system (yes/no)
  • Single-winner/multiple winner system
  • List / candidate (personal election) based system
  • Decision rule
    • Plurality (candidates with most votes win)
    • Majority (candidates must receive support at least half of voters)
    • Quota (candidates must at least reach the quota)
  • Type of ballot
    • single choice
    • multiple choice
    • cumulative (more than one vote for one candidate possible)
    • ranked (ordinal voting)
    • score (cardinal voting)
  • Number of votes/voter
  • Number of tiers: number of levels e.g. local, regional, state, national

Systems

Name(s) Variations Type of representation Mixed? Single/multi-winner List / candidate-based system Type of decision rule Type of ballot Number of votes / voter Number of tiers

(if mixed)

First-past-the-post (FPTP/FPP)[1]

Single-member plurality (SMP/SMDP)

two-round system with lower than 50% requirement in first round majoritarian No single-winner candidate plurality single choice 1 N/A
General ticket

Party-block voting (PBV)

majoritarian No multi-winner list plurality single choice 1 N/A
Plurality block voting (BV)

plurality-at-large voting

(multiple non-transferable vote, MTNV)

limited party block voting majoritarian No multi-winner candidate plurality multiple choice =number of winners N/A
Limited voting (LV)

limited block voting

partial block voting

(multiple non-transferable vote, MNTV)

limited party block voting semi-proportional No multi-winner candidate plurality multiple choice <number of winners N/A
Single non-transferable vote (SNTV) semi-proportional No multi-winner candidate plurality single choice 1 N/A
Single transferable vote (STV)

Hare–Clark electoral system[2]

(proportional ranked-choice voting)[3]

semi-proportional / proportional No multi-winner candidate quota ranked choice (ordinal voting) 1 (effectively) N/A
Instant-runoff voting (IRV)[4]

(Alternative vote - AV)[5]

(Ranked-choice voting - RCV)[6]

(Single-transferable vote - STV)

(Hare's method)[7]

contingent vote,

supplementary vote, Coombs' method

majoritarian No single-winner candidate majority ranked choice (ordinal voting) 1 (effectively) N/A
Two-round system (TRS)[8]

Runoff voting

Non-partisan primary,

multi-round voting

majoritarian No single-winner candidate majority single choice 1 (each round) N/A
Two-round block voting

(majority block voting)(multiple non-transferable vote, MNTV)

majoritarian No multi-winner candidate majority multiple choice =number of winners (each round) N/A
Multiple transferable vote (MTV)

(Preferential block voting)

majoritarian No multi-winner candidate majority ranked choice (ordinal voting) =number of winners, effectively N/A
Exhaustive ballot majoritarian No single-winner /multi-winner candidate majority single choice 1 N/A
Cumulative voting panachage (certain types) majoritarian / semi-proportional No single-winner /multi-winner candidate plurality cumulative ballot >1 N/A
Approval voting (AV)[9] block approval voting majoritarian No single-winner /multi-winner candidate plurality multiple choice any number

(max. one for one candidate)

N/A
Score voting
Range voting 		Approval voting (score voting 0-1) majoritarian / semi-proportional No single-winner /multi-winner candidate plurality score ballot(cardinal voting) N/A
Borda count majoritarian / semi-proportional No single-winner /multi-winner candidate plurality ranked choice (ordinal voting) N/A
Condorcet method Copeland's method,

Dodgson's method, Kemeny–Young method, Minimax, Nanson's method, ranked pairs, Schulze method, Tideman's alternative methods

majoritarian No single-winner candidate majority against every candidate ranked choice (ordinal voting) N/A
Party-list proportional representation

list-PR

Largest remainderHighest averagesBinomial voting semi-proportional / proportional No multi-winner list (+ candidate, if open list) quota or divisor method single choice 1 (effectively) N/A
Superposition - non-compensatory combination of FPTP + List-PR

(Supplementary member system)

(Parallel voting)[10]

(Mixed-member majoritarian representation - MMM)

Two-round system + List-PR

mixed single vote version

semi-proportional Yes multi-winner(+ single-winner in districts) candidate + list mixed non-compensatory single choice 2 (each tier) 2
Seat-linkage compensatory combination of FPTP + List-PR

(Additional member system - AMS)[11]

(Mixed-member proportional representation - MMP)

mixed single vote versionbest-loser mixed-member proportional semi-proportional / proportional Yes multi-winner(+ single-winner in districts) candidate + list mixed compensatory single choice 2 (each tier) 2
Vote-linkage compensatory combination of FPTP + List-PR

Positive vote transfer system (PVT)[12]

(mixed single vote - MSV[13])

(Additional member system - AMS)

negative vote transfer semi-proportional / proportional Yes multi-winner(+ single-winner in districts) candidate + list mixed compensatory single choice 1 2
Dual member proportional (DMP)[14] semi-proportional / proportional Yes multi-winner list or candidate plurality single choice 1 1

List of electoral systems used for national elections

Electoral system for national legislatures

(lower house or unicameral)

Electoral systems map simplified.svg
  Majoritarian representation (winner-take-all)
  Proportional representation
  Mixed-member majoritarian representation
  Mixed-member proportional representation
  Semi-proportional representation (non-mixed)
  No election (e.g. Monarchy)

See also

References

  1. ↑ "First past the post" (in en). Ministry for Culture and Heritage. 13 January 2016. https://nzhistory.govt.nz/politics/fpp-to-mmp/first-past-the-post. 
  2. ↑ George Howatt, Democratic Representation under the Hare-Clark System – The Need for Seven-Member Electorates
  3. ↑ "How RCV Works". https://www.fairvote.org/how_rcv_works. 
  4. ↑ Cary, David (1 January 2011). "Estimating the Margin of Victory for Instant-runoff Voting". Proceedings of the 2011 Conference on Electronic Voting Technology/Workshop on Trustworthy Elections. EVT/WOTE'11: 3. http://dl.acm.org/citation.cfm?id=2028012.2028015. Retrieved 11 June 2022. 
  5. ↑ "Alternative Vote" (in en-US). https://www.electoral-reform.org.uk/voting-systems/types-of-voting-system/alternative-vote/. 
  6. ↑ FairVote.org. "Ranked Choice Voting / Instant Runoff". https://www.fairvote.org/rcv. 
  7. ↑ Pacuit, Eric (3 August 2011). Voting Methods. https://plato.stanford.edu/archives/fall2019/entries/voting-methods/. Retrieved 11 June 2022. 
  8. ↑ "Two-Round System". https://www.electoral-reform.org.uk/voting-systems/types-of-voting-system/two-round-system/. 
  9. ↑ Brams, Steven; Fishburn, Peter (1978). "Approval Voting". American Political Science Review 72 (3): 831–847. doi:10.2307/1955105. 
  10. ↑ "Parallel —". https://aceproject.org/main/english/es/ese01.htm. 
  11. ↑ "Additional-member system: Politics". Encyclopædia Britannica. http://www.britannica.com/topic/additional-member-system. Retrieved 24 March 2016. 
  12. ↑ Bochsler, D (2014). "Which mixed-member proportional electoral formula fits you best? Assessing the proportionality principle of positive vote transfer systems". Representation 50: 113–127. doi:10.1080/00344893.2014.902222. 
  13. ↑ Golosov, G. V. (2013). "The Case for Mixed Single Vote Electoral Systems". The Journal of Social, Political, and Economic Studies. 
  14. ↑ Graham, Sean (April 4, 2016). Dual-Member Mixed Proportional: A New Electoral System for Canada. doi:10.7939/r3-qppp-b676. https://era.library.ualberta.ca/items/e3ab993a-d264-4d30-b819-290ab5fd6b62. Retrieved June 11, 2022. 



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