Mixed electoral system

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A mixed electoral system or mixed-member electoral system is one that combines different types of electoral systems to elect a single assembly. A mixed system may be characterized by one or more of the following:

• It combines a system that provides majoritarian representation with one that provides proportional representation (PR).^[1][2][3] The majoritarian component is usually first-past-the-post voting (FPTP/SMP),^[4] 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^[2] or mixed-member majoritarian, in which case the overall results are semi-proportional, retaining disproportionalities from the majoritarian component.
• It combines local representation^[5] (most often single-member constituencies) with regional or national (multi-member constituencies) representation. Mixed systems may or may not have multiple tiers:^[6] most mixed systems have both local and national/regional tiers (called superposition), but some have only one at-large (national) tier, like the majority bonus system (fusion) or only a single tier for local/regional representation (called coexistence).
• It combines personal elections (where voters vote for candidates) and list elections (where voter vote for electoral lists of parties). In most mixed systems every voter can influence both the district-based and PR aspects of an election^[7] (e.g. under parallel voting), in others, the voter casts just one vote (mixed single vote), which is used to contribute to both a personal (usually district) election and to the filling of seats through list system .^[8] Most mixed systems have all the voters contributing to the election of both groups of members.

In a hybrid system, different electoral formulas are used in different contexts. These may be seen in coexistence, when different methods are used in different regions of a country, such as when FPTP is used in single-member districts and list-PR in multi-member districts, but every voter is a member of only one district (one tier). Some hybrid systems are generally not referred to as mixed systems, such as when as FPTP districts are the exception (e.g. overseas constituency) and list-PR is the rule, the overall system is usually considered proportional. Similarly, when FPTP is in single-member districts and used block voting (or party block voting) is used in multi-member districts, the system is referred to as a majoritarian one, as all components are majoritarian. Most mixed systems are not referred to as hybrid systems

There are also supermixed systems, like rural-urban proportional (RUP), which is a hybrid mixed system that uses STV in urban regions and MMP (itself a mixed system) in rural-regions.^[4] Another supermixed system is scorporo, which is a hybrid of parallel voting and the mixed single vote). ^[9]

The prominent mixed electoral systems are mixed-member proportional representation (MMP) and mixed-member majoritarian representation via parallel voting (FPTP/SMP + party-list PR).

Compensatory/non-compensatory seat allocation[]

A distinction is often made between mixed compensatory systems and mixed non-compensatory systems.^[8] In both types of systems, one set of seats is allocated using a plurality or majoritarian method, usually First past the post. 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.

In mixed non-compensatory systems, such as Parallel voting,^[4] the proportional allocation is performed independently of the district election component.

In 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.

The following hypothetical example based on the one by Massicotte^[4] 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.

Party		Popular vote	FPTP seats	PR seats	Total seats (FPTP + PR)	FPTP seats
	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.

Party	Popular vote	FPTP seats	PR seats (non-compensatory)	Total seats (FPTP + PR)	PR seats (non-compensatory)	Total seats (FPTP + PR)
Party A	44%	64	44	108 (54% of assembly)
Party B	40%	33	40	73 (36.5% of assembly)
Party C	10%	0	10	10 (5% of assembly)
Party D	6%	3	6	9 (4.5% of assembly)
TOTAL	100%	100	100	200

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.

Party	Popular vote	FPTP seats	PR seats (compensatory)	Total seats (FPTP + PR)	PR seats (compensatory)	Total seats (FPTP + PR)
Party A	44%	64	24	88 (44% of assembly)
Party B	40%	33	47	80 (40% of assembly)
Party C	10%	0	20	20 (10% of assembly)
Party D	6%	3	9	12 (6% of assembly)
TOTAL	100%	100	100	200

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.^[10] 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.^[4]

The two common ways compensation occurs are seat linkage compensation (or top-up) and vote linkage compensation (or vote transfer).^[10] 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.^[11]

Types of mixed systems[]

Below is a table of different categories of mixed electoral systems based on the 5 main types identified by Massicotte&Blais.^[7]

Mixed member majoritarian representation (MMM) and parallel voting[]

Parallel voting is a mixed non-compensatory system with two tiers of representatives: a tier of single-member district representatives elected by a plurality/majoritarian method such as FPTP/SMP, and a tier of regional or at-large representatives elected by a separate proportional method such as party list PR. It is used for the first chamber (lower house) in many countries including Japan, South Korea, and Russia.

This type of parallel voting provides semi-proportional results, but is often referred to as mixed-member majoritarian representation, as the lack of compensation means each party can keep all the

Mixed member proportional representation (MMP) and additional member systems[]

Like parallel voting, MMP and AMS also have a tier of district representatives typically elected by FPTP, and a tier of regional or at-large representatives elected by PR. Unlike parallel voting, MMP and AMS are mixed compensatory systems, meaning that the PR seats are allocated in a manner that corrects disproportionality caused by the district tier. MMP corrects disproportionalities by adding as many leveling seats as needed, this system is used by Germany and New Zealand.

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.

Majority bonus and majority jackpot systems[]

Electoral systems with a majority bonus have been referred to as "unconventional mixed systems".^[12] Employed by Armenia, Greece, and San Marino, as well as Italy from 2006 to 2013,^[13] majority bonuses help the most popular party or alliance win a majority of the seats with a minority of the votes, similar in principle to plurality/majoritarian systems. However, PR is used to distribute seats among the opposition parties, and possibly within the governing alliance.

Vote transfer systems[]

Mixed single vote and positive vote transfer (PVT)[]

MSV is a mixed compensatory type of systems using only a single vote that serves both as a vote for a local candidate and as a transfer vote on the compensatory tier. Similar to MMP, proportionality depends on the exact parameters to such a system, but it differs in that vote linkage (vote transfer) is used instead of seat linkage and split ticket voting is not possible. The system was used in Germany,^[11] and is currently used in Hungary for some local elections and in a modified form also for national elections (combined with parallel voting as part of a more complex system).

Scorporo and negative vote transfer (NVT)[]

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.^[14] 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.^[15] The system was used in Italy from 1993 to 2005, and a modified version is currently used in Hungary.^[16] Unlike scorporo, this version uses a positive vote transfer system, in which "wasted" votes (including surplus votes of winners) are added to the results of the party list vote, in this respect it is a hybrid of parallel voting and the mixed single vote.

Other mixed systems[]

Alternative vote plus (AV+)[]

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.

Dual member proportional (DMP)[]

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.

Mixed ballot transferable vote (MBTV)[]

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.^[17] 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.

List of countries using mixed systems[]

The table below lists the countries that use a mixed electoral system for the first chamber of the legislature. Countries with coexistence-based hybrid systems have been excluded from the table, as have countries that mix two plurality/majoritarian systems. (See also the complete list of electoral systems by country.)

Country		Latest election (year)	Type of mixed system	Seats per constituency	Mixed system	Component electoral systems	Total seats	Number of votes	Typical results	Notes
Andorra	General Council	2018	Non-compensatory (MMM)		Supermixed parallel voting (superposition) and additional member system (correction)	Party block voting and party-list PR			semi-proportional
Armenia			Partially compensatory (MMM)		Majority jackpot system	Party-list PR + party block voting (PBV)
Bolivia	Chamber of Deputies	2020	Compensatory	1 (local districts), ? (regional constituencies), 7 (indigenous seats elected by the usos y costumbres)	Additional member system (AMS) - MMP without levelling seats	First-past-the-post (FPTP/SMP) + Party-list PR		1 (double simultaneous vote)	proportional
Georgia	Parliament	2020	Non-compensatory (MMM)						semi-proportional
Germany	Bundestag (lower house of the federal parliament)	2021	Compensatory	1 (local districts), varies (regional constituencies),	Mixed-member proportional representation (MMP) - with levelling seats	Party-list PR + First-past-the-post (FPTP/SMP)	598 + leveling seats	2	proportional	Referred to as personalized proportional representation,[18] in 1949 as a result of inter-party bargaining.[19] Originally used single vote version, switched to two vote version before the 1953 election.
	State parliaments, except Bremen, Hamburg Saarland	varies by state	Compensatory	varies by state	Mixed-member proportional representation (MMP) - with levelling seats	Party-list PR + First-past-the-post (FPTP/SMP)	varies by state	varies by state		Bavaria uniquely uses an open-list system for its party-list seats. Baden-Württemberg uses MMP without lists.
Greece			Non-compensatory (MMM)		Majority bonus				semi-proportional
Guinea	National Assembly	2020	Non-compensatory (MMM)	1 (local districts), 76 (national constituency)	Parallel voting / superposition	Party-list PR (Hare quota) + First-past-the-post (FPTP/SMP)			semi-proportional
Hungary	National Assembly (Országgyűlés)	2018	Partially compensatory (MMM)	1 (local districts), 93 (national constituency)	Supermixed: parallel voting (superposition) and positive vote transfer (correction)	First-past-the-post (FPTP/SMP) + national list-PR			semi-proportional
Italy	Chamber of Deputies	2018	Non-compensatory (MMM)		Superposition	List PR + First-past-the-post (FPTP/SMP)			semi-proportional	mixed single vote
	Senate	2018	Non-compensatory (MMM)		Superposition	List PR + First-past-the-post (FPTP/SMP)			semi-proportional	mixed single vote
Republic of Korea (South Korea)	National Assembly	2020	Partially compensatory (MMM)	1 (local districts), 17 supplementary seats (parallel voting), 30 additional seats (AMS),	Supermixed parallel voting (superposition) and additional member system (correction)	Party-list PR + First-past-the-post (FPTP/SMP)			semi-proportional
Kyrgyzstan	Supreme Council	2021	Non-compensatory (MMM)	1 (local districts), 54 (nationwide constituency)	Parallel voting / superposition	Party-list PR + First-past-the-post (FPTP/SMP)			semi-proportional
Japan			Non-compensatory						semi-proportional
Lesotho			Compensatory		Additional member system (AMS)			1 (mixed single vote)	proportional
Lithuania			Non-compensatory (MMM)						semi-proportional
Mauritania			Non-compensatory (MMM)
Mexico	Chamber of Deputies	2021	Partially compensatory (MMM)	1 (local districts), 40 (multi-member districts)	Supermixed parallel voting (superposition) and additional member system (correction): Since 1996, a party cannot get more seats overall than 8% above its result nationally (i.e., to win 50% of the legislative seats, a party must win at least 42% of the vote nationwide). There are three exceptions on this rule: first, a party can only lose PR-seats due to this rule (and no plurality-seats); second, a party can never get more than 300 seats overall (even if it has more than 52% of the vote nationally); and third, a party can exceed this 8% rule if it wins the seats in the single-member districts.	First-past-the-post (FPTP/SMP) + Party-list PR (Largest remainder:Hare quota)		2	semi-proportional
	Chamber of Senators	2018	Non-compensatory (MMM)	3 (local districts), 32 (multi-member districts)	Superposition	Limited (party) block voting locally (2 seats from each constituency to largest party, 1 to the second largest party) + Party-list PR nationwide		1		single vote
Monaco			Non-compensatory (MMM)
Mongolia			Non-compensatory (MMM)
Morocco			Non-compensatory (MMM)
Nepal			Non-compensatory (MMM)
New Zealand			Compensatory		mixed member proportional (MMP)
Philippines			Non-compensatory (MMM)
Russia			Non-compensatory (MMM)
San Marino			Majority bonus						semi-proportional
Scotland			Compensatory		Additional member system (AMS)				semi-proportional
Senegal			Non-compensatory (MMM)
Seychelles			Non-compensatory (MMM)
Sri Lanka			Non-compensatory (MMM)
Taiwan			Non-compensatory (MMM)
Tajikistan			Non-compensatory (MMM)
Tanzania			Non-compensatory (MMM)
Thailand			Compensatory		Additional member system (AMS)			1 (mixed single vote)	proportional
Ukraine			Non-compensatory (MMM)						semi-proportional
Venezuela			Non-compensatory (MMM)
Wales			Compensatory		Additional member system (AMS)				semi-proportional
Zimbabwe			Non-compensatory (MMM)

See also[]

• Electoral systems
• List of electoral systems by country
• Proportional representation
• Semi-proportional representation
• Representative democracy
• Types of democracy

References[]

External links[]

• Chamber 1 Electoral Systems Map from the ACE Electoral Knowledge Network