Semi-proportional representation


Semi-proportional representation characterizes multi-winner electoral systems which allow some representation of smaller parties or candidates, but produce results that do not always reflect the strength of the competing political forces in a way that is proportional to the shares of the votes they receive. Semi-proportional voting systems are between proportional systems like party-list proportional representation or single transferable vote and winner-take-all systems. Examples of semi-proportional systems include the single non-transferable vote, limited voting, and parallel voting.
There are different measures of proportionality, and no objective threshold, so opinions differ on what constitutes a semi-proportional system, a non-proportional system and a proportional system.

Single-vote systems

Semi-proportional systems

Election systems in which a party can achieve its due share of seats and achieve approximately-proportional outcomes while maintaining simplicity and reducing the cost of election administration. Under these systems, parties may coordinate voters by limiting the size of the party slate or by using complex vote management schemes where voters are asked to randomize which candidate they support or vote in specified ways, such as through differently-worded voting cards.
These systems are notable for the absence of an ordered party list. Candidates may coordinate their campaigns, and present or be presented as agents of a party, but voters may choose to support one candidate among the said group but not the others.

Single transferable vote

Some writers consider the single transferable vote to be semi-proportional because of its favoritism towards major parties, sometimes caused by a combination of the Droop quota in small districts, as well as the vote management that may be involved when optional preferential voting is used, producing exhausted ballots. On the other hand, some describe it as proportional on the grounds that it is proportional in the limit of infinitely-large constituencies. However, on party basis, if first preferences are used as guide, STV is only proportional for solid coalitions, if voters rank candidates along party lines and no significant number of votes cross party lines. The proportionality of STV, as measured by first preferences, breaks down if voters are split across party lines or choose to mark preferences candidates of different parties. Under STV, each elected member is elected by the exact same number of votes or something very close to it, so proportionality is produced that way.

Partisan systems

Other forms of semi-proportional representation are based on, or at least use, party lists to work. Looking to the electoral systems effectively in use around the world, there are three general methods to reinforce the winner-take-all principle of representation starting from basic PR mechanisms: parallel voting, the majority bonus system, and extremely reduced constituency magnitude.
In additional member systems, the number of additional members may not be sufficient to balance the disproportionality of the original system, thereby producing less than proportional results. When this imbalance is created intentionally, the result could be described as a semi-proportional system — for example, in the Welsh Senedd, where only 33.3% of members are compensatory. The electoral system commonly referred to in Britain as the "additional member system" is also used for the Scottish Parliament and the London Assembly, with generally proportional results. Similarly, in vote transfer based mixed single vote systems, the number of compensatory seats may be too low to achieve proportionality. Such a system is used in Hungary in local elections. The "scorporo" system used for the Parliament of Italy from 1993 to 2005 and the electoral system for the National Assembly of Hungary since 1990 are also special cases, based on parallel voting, but also including compensatory mechanisms – which however are insufficient for providing proportional results.
A majority bonus system takes an otherwise proportional system based on multi-member constituencies, and introduces disproportionality by granting additional seats to the first party or alliance. Majority bonuses help produce landslide victories similar to those which occur in elections under plurality systems. The majority bonus system was first introduced by Benito Mussolini to win the election of 1924. It has remained in use in Italy, as well as seeing some use in San Marino, Greece, and France.
The simplest mechanism to reinforce major parties in PR system is to severely restrict the number of seats per electoral district, which increases the Droop quota.
The last main group usually considered semi-proportional consists of parallel voting models. The system used for the Chamber of Deputies of Mexico since 1996 is considered a parallel voting system, modified by a list-seat ceiling for over-representation of parties.

Usage

CountryLegislative bodyLatest election Type of majoritarian systemElectoral systemTotal seatsGovernmental systemNotes
AndorraGeneral Council2018Mixed-member majoritarian2 / 14 Parallel voting / superposition :
Party block voting locally + list PR nationwide		28Parliamentary system
Democratic Republic of the CongoNational Assembly2018Mixed-member majoritarian1–17Coexistence mixed majoritarian :
First-past-the-post in single-member districts and List PR in multi-member districts 		500
DjiboutiNational Assembly2018Mixed-member majoritarian3–28Fusion / majority jackpot :
80% of seats in each constituency are awarded to the party receiving the most votes, remaining seats are allocated proportionally to other parties receiving over 10% 		65Presidential system
FranceFrench Polynesia Assembly2018Mixed-member majoritarian4–17Two-round majority bonus system in multi-member constituencies57
GeorgiaParliament2020Mixed-member majoritarian1,
120 		Parallel voting / superposition :
Party-list PR + First-past-the-post 		150Parliamentary system
GreeceMixed-member majoritarianMajority bonus system
GuineaNational Assembly2020Mixed-member majoritarian1,
76 		Parallel voting / superposition :
Party-list PR + First-past-the-post 		114
HungaryNational Assembly 2018Mixed-member majoritarian1, 93 Supermixed / Mixed-member majoritarian :
First-past-the-post + national list-PR for 93 seats 		199Parliamentary systemBefore the 2014, a different mixed system was used with a two-round system in single-member districts
IraqSingle non-transferable vote
ItalyChamber of Deputies2018Mixed-member majoritarian1, 12, ?-? Superposition / Mixed-member majoritarian using a single vote
List PR + First-past-the-post 		630Parliamentary system
ItalySenate2018Mixed-member majoritarian1, 6, ?-? Superposition / Mixed-member majoritarian using a single vote
List PR + First-past-the-post 		315Parliamentary system
Republic of Korea National Assembly2020Mixed-member majoritarian1, 17 supplementary seats, 30 additional seats,Supermixed / Mixed-member majoritarian :
First-past-the-post and List PR 		300Presidential system
KuwaitSingle non-transferable vote
KyrgyzstanSupreme Council2021Mixed-member majoritarian1, 54 Parallel voting / superposition :
Party-list PR + First-past-the-post 		90Presidential system
LithuaniaSeimas2020Mixed-member majoritarian1, 70 Parallel voting / superposition :
Two-round system for 71 seats + List PR for 70 seats		141Semi-presidential system
MadagascarNational Assembly2019Mixed-member majoritarian1–2Coexistence: First-past-the-post in 87 single-member districts, party-list PR in 32 two-member districts 151Semi-presidential system
MauritaniaNational Assembly2018Mixed-member majoritarian1–3, 40 Coexistence+superposition ''supermixed/hybrid:
Two-round system in single-member districts, two-round block voting in dual-member districts, and List PR in larger districts + twice 20 nationally List PR 		157Semi-presidential system
MonacoNational Council2018Mixed-member majoritarian24 Superposition / Mixed-member majoritarian using a single ballot:
Plurality block voting in single nationwide constituency for 16 seats; D'Hondt method 		24Parliamentary system
PalestineLegislative Council2006Mixed-member majoritarian1–9, 66 Parallel voting / superposition :
First-past-the-post in single-member districts and Plurality block voting in two-seat districts for 66 seats in total + List PR for 66 seats		132Semi-presidential systemIn the 1996 elections, 88 PLC members were chosen from several multi-member constituencies via block voting
PanamaNational Assembly2019Mixed-member majoritarianCoexistence mixed majoritarian :
First-past-the-post in single-member districts, Saripolo or Sartori method in multi-member districts		71Presidential system
PhilippinesHouse of Representatives2019Mixed-member majoritarian1, 61 Parallel voting / superposition :
First-past-the-post in single-member districts + List PR 		304Presidential system
Russian FederationState Duma2021Mixed-member majoritarianParallel voting / superposition :
First-past-the-post and List PR		450Semi-presidential system
San MarinoMajority bonus system Parliamentary system
ScotlandParliament2021Mixed-member majoritarian73, 56 Additional Member System 129Parliamentary system
Senegal2017Mixed-member majoritarianParallel165Presidential system
Seychelles2020Mixed-member majoritarianParallel35Presidential system
Singapore2020Mixed-member majoritarianFirst-past-the-post and party block voting 104
Sudan2015Mixed-member majoritarianParallel450
SwitzerlandCouncil of States
Only in:names of cantons''		2Single non-transferable vote 46
Taiwan2020Mixed-member majoritarianParallel113
Tajikistan2020Mixed-member majoritarianParallel63
Thailand2019 Mixed-member majoritarianParallel500The next election is scheduled to be held under parallel voting again, after one election held using a single vote MMP system
British Overseas Territories GibraltarLimited voting
British Overseas Territories Pitcairn IslandsSingle non-transferable vote
VanuatuSingle non-transferable vote
VenezuelaNational Assembly2020Mixed-member majoritarianParallel voting :
First-past-the-post and list PR		280 Presidential system
ZimbabweNational Assembly2018Mixed-member majoritarian1,
10 		Mixed-member majoritarian :
210 seats by first-past-the-post in local districts
60 seats reserved for women by list PR		270Presidential systemVoters cast a single vote