List Methods of Proportional Representation
With list PR, and voters vote for a list of candidates, rather than (or in addition to) voting for individual candidates. Each list, often a party list, is allocated its share of seats based on its proportion of the total vote, so that a list with 30% of the vote wins 30% of the seats, and so on. There is typically a threshold such that parties receiving less than some percentage of the vote (typically in the 1–5% range) win no seats at all. If a list wins enough votes to elect five seats, for example, the first five candidates on that list are elected.
In closed-list systems, each list of candidates, along with its order, is determined by the party before the election. The voter votes for a list only, and not for individual candidates.
Closed-list PR is used in Norway, Israel, Iraq, South Africa and Peru, among other places.
In open-list systems, voters vote for one or more candidates on a list, and those votes determine (or at least influence) the order in which candidates are seated.
Open-list systems are used in Finland, Sweden, Brazil, and the Netherlands, among other places.
Mixed-Member PR Systems
In a mixed-member list system, one set of candidates is elected non-proportionally from single-member districts. These “constituency seats” are intended to guarantee geographically local representation. A second set of “list seats” is elected via a list-PR system, either open or closed. These seats are allocated to parties such that the overall list representation (including both constituency and list seats) is proportional.
(Mixed-member systems are often referred to as MMP, for mixed-member proportional, but we’ll avoid that abbreviation in favor of MMPR because of confusion with multi-member plurality systems, which are not proportional at all.)
Mixed-member PR is used in Germany, New Zealand, Bolivia and Italy, among other places.