Draft:Supermixed electoral system

Rural-urban proportional is a supermixed, coexistence based electoral system: a combination of STV and MMP systems.

A supermixed electoral system is a type of mixed electoral system which uses more than one type of combination two create a hybrid of two or more electoral systems^[1]. Most often, this involves a winner-take-all component combined with a proportional component.^[2] The results of the combination may be mixed-member proportional (MMP), where the overall results of the elections are proportional,^[3] or mixed-member majoritarian, in which case the overall results are semi-proportional, retaining disproportionalities from the majoritarian component.

Rural-urban proportional (RUP), which is a hybrid mixed system that uses two tiers: the lower tier uses a proportional system, like list-PR or STV, in urban regions, and the upper tier uses MMP (itself a mixed system) either in rural regions alone or in all regions.^[4]

^[5]^[3]^[6] ^[7]^[1]

Types of mixed systems

Types of combinations

Apart from the compensatory/non-compensatory typology, a more detailed classification is possible based on how component systems relate to each other, according to academic literature. Below is a table of different categories of mixed electoral systems based on the five main types identified by Massicotte & Blais.^[8] According to their terminology, methods of compensation are referred to as compensation is referred to as correction, while another type of dependent combination exists, called the conditional relation between sub-systems. Meanwhile, independent combinations mixed systems might 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).

There are also supermixed systems,


Combination	Type	Attributes	System	Example(s) for use
Independent combination	Fusion	Two formulas are used within each district (or one district for the whole electorate)	Majority bonus (MBS)	France (local), French Polynesia^{[citation needed]}
	Coexistence (hybrid)	Different districts use different systems in one tier	e.g. FPTP/SMP in single-member districts, list-PR in multi-member districts	Democratic Republic of the Congo, Panama
	Superposition	Different tiers use different systems	Parallel voting (e.g. FPTP/SMP locally, list-PR nationally)	Lithuania, Russia
	Superposition	Different tiers use different systems	Single vote mixed-member majoritarian (e.g. FPTP/SMP locally, list-PR nationally)	Italy, Pakistan
Dependent combination	Correction (compensation)	One formula uses the results of other to compensate	Seat linkage mixed system with partial correction for overhang seats: New Zealand's mixed-member proportional representation (MMP)	New Zealand
			Seat linkage mixed system with no correction for overhang seats: UK Additional member system (AMS) - a less proportional version of MMP	Scotland
			Single vote with seat linkage (for mixed-member proportional representation)	Lesotho
			Single vote with compensatory vote transfer (semi-proportional)	Hungary (local)
	Conditional	Outcome of one formula determines the other formula	e.g. conditional party block voting: party that receives more than 50%, gets all seats otherwise all seats distributed proportionally	-
Combination of combinations	Supermixed	Superposition + correction	Scorporo / negative vote transfer (NVT), Parallel voting + PVT	Hungary
		Superposition + correction	Parallel voting + AMS	South Korea
		Superposition + fusion	National plurality bonus in regional list-PR	Greece
		Superposition + coexistence	e.g. some elected by PR in single national district, some are elected locally by plurality	Ecuador^[8]
		Coexistence + conditional	e.g. FPTP/SMP in single-member districts, conditional party block voting in multi-member districts	Cameroon, Chad
		Coexistence + correction	Rural-urban proportional representation (RUP)	Denmark (formerly), Iceland (formerly)
		Conditional + correction + fusion	Majority jackpot systems, particularly two-round variants	Armenia, San Marino
		Fusion + correction	Dual-member proportional representation (DMP)	-

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

Dual member mixed proportional (DMP) is a mixed compensatory system using the same principle as more common variants of 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.

Vote linkage compensatory systems

Vote linkage compensatory systems are an alternative to seat linkage compensation, currently only used in Hungary as part of a supermixed system. Such systems in use have been (inaccurately^[9]) described as mixed member proportional, but they were more commonly between MMP and MMM in nature, or closer to mixed-member majoritarian representation, offering little compensatory power.

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.^[10] 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.^[11] The system was used in Italy from 1993 to 2005

Majority jackpot systems

Electoral systems with a majority bonus or jackpot have been referred to as "unconventional mixed systems"^[12], which fall into the mixed-member majoritarian type, but they may be compensatory (jackpot) or non-compensatory (bonus). 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 the rest of seats (sometimes only among the opposition parties) and possibly within the governing alliance.

Number of votes

Double vote

Most mixed systems allow voters to cast separate votes for different formulas of the electoral system, including:

Parallel voting
Most AMS/MMP systems
AV+ (the first vote is ranked)
Scorporo

List of countries using mixed systems

The table below lists the countries that use a mixed electoral system for the primary (lower) 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	Body	Latest election (year)	Type of mixed system	Seats per constituency	Mixed system	Component electoral systems	Total seats	Number of votes	Typical results	Notes
Armenia			Partially compensatory		Majority jackpot system	Party-list PR + party block voting (PBV)			semi-proportional
Djibouti	National Assembly	2018		3-28			65		semi-proportional	80% of seats (rounded to the nearest integer) in each constituency are awarded to the party receiving the most votes (party block voting), remaining seats are allocated proportionally to other parties receiving over 10% (closed list, D'Hondt method)
Greece	Hellenic Parliament	2019	Non-compensatory		Majority bonus				semi-proportional
Hungary	National Assembly (Országgyűlés)	2018	Partially compensatory	1 (local districts), 93 (national constituency)	Supermixed: parallel voting (superposition) and positive vote transfer (correction)	First-past-the-post (FPTP/SMP) + national list-PR	199	2	semi-proportional
Japan	House of Representatives	2021	Non-compensatory	1 (local districts)	Parallel voting (superposition)	First-past-the-post (FPTP/SMP) and List PR	465	2	semi-proportional
Japan	House of Councillors		Non-compensatory		Parallel voting (superposition)	SNTV and List PR		2	semi-proportional
Republic of Korea (South Korea)	National Assembly	2024	Partially compensatory	1 (local districts), 46 additional seats (AMS)	Additional member system (AMS)	Party-list PR + First-past-the-post (FPTP/SMP)	300	2	(semi-)proportional	From 2019 to 2024: supermixed parallel voting (superposition) and additional member system (correction), with 253 single-member constituencies, 17 supplementary seats (a la parallel voting), and 30 compensatory seats (AMS) Since 2024 only additional member system
Mexico	Chamber of Deputies	2021	Partially compensatory	1 (local districts), 40 (multi-member districts)	Supermixed parallel voting (superposition) and additional member system (correction)	First-past-the-post (FPTP/SMP) + Party-list PR (Largest remainder:Hare quota)		2	semi-proportional	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.
San Marino	Grand and General Council	2019	Non-compensatory		Majority jackpot				proportional (first round)