Proportional representation

Proportional representation refers to the fair and accurate translation of citizen and party makeup into the legislature. If X percent of voters support a certain party, then X percent of the legislature should mirror that party. Proportional representation voting systems are comprised of three main variations: the party list system, the mixed-member system, and the single transferable vote (or choice voting).

Input: multimember districts, diverse voting base, intentional (oftentimes low) exclusion threshold

Output: multiparty representation, proportional allocation of seats, potential for minority party representation

Background

Proportional representation voting systems came about as a reaction to the inaccurate representation of parties that frequently occurred in the plurality and majority voting systems. In the late 19th and early 20th centuries, many European countries began to realize the need for increasingly diverse parties to have a fair share of seats as suffrage expanded voter pools. The shift to proportional representation occurred for most European countries by 1920; Western democracies mirrored this trend throughout the 20th century.

Feedback loops

Sensitivities

Fair and accurate representation for multiple parties, leading to more nuanced policies
More accurate representation for marginalized groups
Votes are more meaningful; voting for a particular candidate doesn’t “take away” from another
Potential for smaller parties to gain representation
Research demonstrates higher voter turnout in PR systems

Oversights

May produce a fractured legislature of too many parties
Can create instability due to lack of majority consensus
Parties that form coalitions may become incredibly strong and therefore difficult to remove from power
Small parties may have exceptional power in tipping a decision between majority parties
May create space for extremist parties to gain power

Implementations

Communities

Many Western democracies use PR systems, including Sweden, Denmark, Finland, Norway, Netherlands, Germany, Belgium, and Ireland.

Tools

Various formulas exist to calculate the allocated number of seats based on election results, including the D’Hondt Method or Jefferson method, Hare method, and German method.
Each variation of the PR system has a different ballot design.
The ACE Project provides extensive information on PR systems and the variations of this system with example ballots and formulas

Further resources

ACE Project: The Electoral Knowledge Network. "Proportional Representation".
Amy, D. J. (2000). Behind the ballot box: a citizen's guide to voting systems. Greenwood Publishing Group.

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