Mixed electoral system

A mixed electoral system is an electoral system that combines a plurality/majoritarian voting system with an element of proportional representation (PR).[1][2][3] The plurality/majoritarian component is usually first-past-the-post voting (FPTP),[4] whereas the proportional component is most often based on party list PR.[5] A distinguishing characteristic of mixed systems is the fact that every voter can influence both the plurality/majoritarian and PR aspects of an election.[6] In a hybrid system, by contrast, different electoral formulas simultaneously, these may manifest in coexistence, when are different methods are used used in different regions of a country[4] or when a parallel system is combined with a vote transfer system (e.g. scorporo).

The most prominent mixed electoral systems include mixed-member proportional representation (MMP) and parallel voting, of which the latter is also known as mixed member majoritarian (MMM). MMP generally produces proportional election outcomes,[2] meaning that a political party which wins n% of the vote will receive roughy n% of the seats. Parallel voting tends to produce semi-proportional outcomes: more proportional than a plurality/majoritarian system but less proportional than a PR electoral system. Both parallel voting and MMP feature two tiers of elected representatives: one associated with the plurality/majoritarian component and one associated with PR. It is not necessary, however, for a mixed system to have multiple electoral tiers.[7]