Vote linkage
The vote linkage or vote transfer system is type of compensatory mixed electoral system, where votes may be transferred across multiple tiers of an electoral system, in order to avoid wasted votes - in contrast to the more common seat linkage compensatory system. It often presupposes and is related to the concept of the mixed single vote, which means that the same vote can be used in multiple tiers of an electoral system and that a vote for a local candidate may automatically count as a vote for the candidate's party or the other way around. Voters usually cast their single vote for a local candidate in a single-member district and then all the wasted votes from this lower tier are added to distribute seats between upper tier candidates, typically national party lists.
Partially compensatory multi-tier vote linkage is an equivalent of the indirect single transferable vote among multi-tiered electoral systems. A related concept is seat linkage, where it is not the votes used in one tier that connect two tiers, but the number of seats a party achieved on the lower tier that is taken into account. A vote linkage system, when applied in a compensatory way takes into account the number of votes that were effective or wasted in the lower tier and takes this into account in the apportionment of the upper tier.
Vote linkage systems currently or formerly used for various national or local elections in Germany, Hungary and Italy have been sometimes described as mixed-majoritarian, or a unique system between MMM and MMP. Some supermixed systems use vote linkage together with parallel voting in a two-vote setup, where split ticket voting is allowed. How proportional the outcome depends on many factors including the vote transfer rules, such which votes are recounted as party list votes, and other parameters used in the system. The vote linkage system originates from Germany and is currently used in Hungary. A version called scorporo was also used in Italy from 1993 to 2005.
Example
Compared to other mixed systems
Terminology
may use vote linkage compensation, meaning not all, but only 'wasted' votes get transferred as list votes to the other tier. Some uncommon, supermixed systems use of MSV may add or subtract the discounted list results to establish a vote linkage based element of compensation into system that would otherwise be categorised as parallel voting. Either type of system is misleadingly known in Hungarian as a "fractional vote recounting system", however, there are no fractional votes used in any variation, the name merely alluding to only a fraction of votes being "recounted" as list votes.The third type of mixed single vote system is the single vote equivalent of parallel voting, which uses the same vote on both the majoritarian and proportional tiers. This makes such systems non-compensatory, falling under the superposition type of mixed systems identified by Massicotte & Blais.
Positive and negative vote transfer
The first recorded mixed vote transfer systems have been under the "losers plus surplus" model, therefore, they inherently included "winner compensation". Under later definitions of certain sources, this model would also be retroactively a "negative vote transfer system" despite not using any votes with negative transfer value. The confusion stems from the terms "positive" and "negative vote transfer system" being coined based on the systems in use in the 1990s and early 2000s in Hungary and Italy and the inconsistent terminology of sources on these niche variants. While all the Hungarian versions primarily transferred votes with a positive value and the votes transferred were almost exclusively in compensation for losing candidates, the Italian models of scorporo operated only with a negative value and deducted all or a part of votes cast for local winners.In one view, positive vote transfer means vote transfer with only positive votes value, with or without winner compensation. This means that either only the positive transfer votes are used on the list tier to apportion seats, or they are added to other list votes. Negative vote transfer systems, meanwhile use the opposite principle, they subtract exactly those votes, which the equivalent positive vote transfer would not transfer. In this way, these systems rely on negative value winner compensation, which is their most important property that determines how they can be manipulated.
In some sources, the Hungarian model of "losers only" has been labeled "positive vote transfer", under this view the Italian Senate model, despite using only negative transfer votes would also be PVT, since it operates under the same "losers only" principle. Conversely "negative vote transfer" means not only the Italian Chamber model of scorporo is, but the original German variants and the current Hungarian electoral systems for national elections. A third term of "direct vote transfer" has been used for vote transfer systems without compensation. This view has been criticized for using unintuitive terminology and not including models of winner compensation other than the surplus votes compared to the second place candidate. This article uses the former view to maintain consistency and to show the significance of positive/negative transfers on manipulation more intuitively.
Controversy on winner compensation
Though the original vote linkage systems used the "losers plus surplus" model, the systems established in Hungary only used votes cast for losing candidates on the compensatory tier of the electoral systems. For this reason, when the system for the National Assembly was changed by the governing parties before the 2014 election, the introduction of transferring surplus votes was a novel element in the system. This element was soon called "winner compensation", who claimed it was effectively a majority bonus. Together with other criticisms of the change this was viewed as a thinly veiled attempt to benefit the parties who created the system, without meaningful consultation of the opposition.Similar proportional systems
Some non-mixed systems, which use multi-member constituencies either on their single tier or also on their lower tier use vote linkage. An example is the national remnant system of Weimar Germany. This system used an absolute quota instead of plurality to elect candidates. With the fixed quota and a changing population, this meant a flexible parliament size.The vote transfer to party list is the mixed single vote equivalent to indirect single transferable voting, while the direct equivalent to the single transfer vote is the mixed ballot transferable vote.
Advantages and disadvantages
The features of vote linkage compensatory systems are similar to those of comparable parallel voting or mixed-member proportional systems, depending on which systems does the result more resemble. As mixed systems they usually inherit properties of their subsystems, in case of the most commonly used vote linkage systems, these are first preference plurality and closed list PR. Single vote variants also suffer from the disadvantages of the mixed single vote, however in certain systems this also gives robusticity against strategic manipulation.Representation for smaller parties
Vote linkage systems generally give greater representation to smaller parties than parallel voting with the same amount of list seats, but usually not as much as comparable seat linkage systems - they usually cannot guarantee overall proportionality. Large parties can win very large majorities, disproportionate to their percentage vote, especially when vote linkage is employed in a supermixed system combined with parallel voting. In Hungary for example, in last 3 elections have resulted in a 2/3 supermajority of seats for the most popular list from at low as 45% of the vote in 2014.Two types of representatives
Because some candidates are elected from constituencies and some from a list, there is a critique that two classes of representatives will emerge under any mixed system, including vote linkage ones: One class beholden to their electorate seat, and the other concerned only with their party. Some consider this as an advantage as local as well as national interests will be represented. Some prefer systems where every constituency and therefore every constituent has only one representative, while others prefer a system where every MP represents the electorate as a whole as this is reflected in the electoral system as well, while a vote linkage mixed system provides a compromise between these two views.Compared to seat linkage and parallel voting
Vote linkage systems can be compared to the mixed-member proportional systems / additional member system and the common form of mixed-member majoritarian representation, parallel voting.Like in parallel voting, a party that can gerrymander local districts can win more than its share of seats. So parallel systems need fair criteria to draw district boundaries.
Seat linkage and vote linkage systems both suffer from different potential manipulation strategies arising from their compensatory component, which the following table shows. Parallel voting does not suffer from these by definition, since the worst case of strategic manipulation reverts compensatory systems to parallel voting.