PR Basics

What is Proportional Representation?

What exactly do we mean by “proportional representation”, or PR?

PR is a property of electoral systems in which the makeup of the elected body closely matches the makeup of the voters, as expressed through their ballots. PR stands in contrast to majority-take-all systems, in which a majority (often a plurality) of voters controls the makeup of the body.

In PR systems, a majority of voters still elect a (representative) majority of a legislative body, but smaller groups have the power to elect their own representatives as well, directly via the ballot.

What PR is not

There are other meanings of the term “proportional representation”. To avoid confusion, we’ll mention some of them, noting that this is not what we’ll be talking about.

  • Population proportionality. The 435 seats in the US House of Representatives are allocated (mostly) proportionately by population to the various states. Here the proportionality is a function of state population, not of voters in an election.
  • Geographic proportionality. Many elected bodies in the US are elected from single-seat districts, in which a degree of geographic proportionality is guaranteed, at the expense of any other basis for proportionality. PR systems permit voters to vote on a geographic basis, but it’s seldom their highest priority.
  • Redistricting. Within a state, congressional districts, as well as state legislative districts, are drawn so that each elected member represents roughly the same number of constituents. This is a kind of proportionality, in that each member represents the same proportion of the statewide electorate, but again it’s not what we’ll be talking about here.
  • Other quotas. Some systems allocate some number of seats in advance to some subgroup of candidates. This might be gender (the Democratic and Republican Parties mandate a degree of gender balance in their National Committees) or another criterion, such as a quota of party members on legislative committees.

When we talk about proportional representation, we mean proportionality based on voter preference expressed through an election — not proportionality or quota mandated by some predetermined characteristic, whether geography, gender, party membership, or anything else.

STV and List PR

While the principle of proportional representation is our primary concern, implementing PR requires a voting mechanism. In most PR systems, voters express their preferences in one of two ways: single transferable vote (STV PR), or list PR.

Under the single transferable vote (STV), voters rank individual candidates in order of preference, and an STV counting system arrives at proportionality based only on individual voter preferences, without regard to party membership of either voters or candidates (thus STV PR is especially useful for non-partisan elections). STV PR is used in Ireland, for the Australian Senate, and for some local elections in New Zealand and Scotland. In the US, STV PR is used for local elections in Cambridge MA and Minneapolis MN.

In list PR systems, each vote counts toward a list (often a party list) rather than for a candidate, and the winners are taken from a list of candidates prepared in advance, often by each party. A list that wins 30% of the total vote is awarded 30% of the legislative seats. If that happens to be 25 seats, then the top 25 candidates on that list are elected. In open-list systems, the voter expresses a preference for a particular candidate, which affects that candidates position on the list. List PR systems come in many different variations, but the general idea is the same. List PR systems are very widely used, for example in Germany, all of Scandinavia, Switzerland, Brazil (and many other South and Central American countries), Iraq and Israel.


One Response to PR Basics

  1. John B. Hodges says:

    These concepts, STV and Party List, can be usefully combined, in a method I call “Candidate List”. All candidates are eligible for all open seats (if necessary, the country might be subdivided into large districts of ten seats each.) Each candidate is required to post, in advance of the election (say, two weeks in advance) a list of all the candidates for that election, IN ORDER OF that candidate’s preference. Voters cast a ballot for their single favorite candidate, or (alternatively) their favorite for each open seat; so (if using this alternative) a voter could vote for the same candidate for each open seat, or distribute their votes to several candidates, in the style of “cumulative voting”. So, the voters face a simple ballot, they do not have to rank a long list of candidates; the ballots can be tallied in local polling places and the totals sent to the central election administration. The totals for each candidate, together with that candidate’s ordered list, are used as the input data for an STV election. See

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