Saylor.org's Comparative Politics/Proportionality and Election Thresholds in Parliamentary Systems
Proportional Representation, Single-Member Plurality, and Mixed Representation
In a proportional representation system, parties are allotted seats in the legislature based on the percentage of the votes that they receive in the polls. Each voter will select a party instead of an individual candidate, after which parties will be assigned seats according to percentages. In many countries there is a threshold that a party needs to pass before getting a seat (generally between 2 - 5 percent). The seats that would have gone to parties receiving under this threshold are divided up by the parties that passed the threshold. Some countries using proportional representation include Israel, Italy, and Iraq.
In a single-member plurality system, members are elected to the legislature from electoral districts. Only one member can be elected from each district. The member who is elected is the person who receives the most votes in that district, even if he does not receive a majority of the vote. Some countries that use this system are the United States and Britain.
In a mixed representation system, some members are elected from electoral districts after receiving a plurality of the vote, while the rest of the seats in the legislature are assigned according to proportional representation. Voters in these countries generally vote for a candidate and a party. Countries employing mixed systems include Russia and Mexico.
A single-member system favors major parties, and will generally allows for only two or three healthy major parties. In the US, for example, only Democrats or Republicans typically win seats; in Great Britain, only the Labour, Conservative, and Liberal parties win seats. This forces the parties to moderate to gain votes and may make compromise in government easier.
A proportional system allows smaller parties to gain seats. This will result in many views represented in the legislature but may make the government less stable. In addition, it may be difficult to employ in a big country because the votes of the entire nation need to be pooled and then divided. A recount in a close election would therefore be impractical.
The British Electoral System
The predominant form of political participation in the United Kingdom is voting. It is from elections that governments derive their legitimacy and competitive elections are a defining feature of democracy. This necessitates a great interest in the multitude of methods by which governments are elected. Academics the world over have evaluated and discussed the vices and virtues of different systems, but a universal standard has yet to be achieved. Below the evidence advocating and opposing the various systems will be evaluated in addition to the debate surrounding electoral reform, an increasingly salient issue, following the election in 1997 of a Labour government committed to a referendum on reform of the electoral system.
First-past-the-post (or simple plurality) is the electoral system utilized for General Elections in the United Kingdom. First-past-the-post is used to elect one candidate in a single member constituency, with the winning candidate requiring only one more vote than their nearest opponent.
A widely celebrated characteristic of first-past-the-post is its history of creating large single party governments, and as the strength of a government is derived from the size of its majority, capable of strong governing. Furthermore, the strong and easily understood link between the electorate and their representative under first-past-the-post creates a climate in which the electorate can easily hold their representative accountable. The simplicity of first-past-the-post, requiring the voter to mark only an 'X' to indicate their favoured candidate, is a feature which allows first-past-the-post to ensure that votes are seldom wrongly cast reducing the extent to which electoral difficulties distort the representativeness of the election.
The results of use of first-past-the-post has generated considerable debate regarding electoral reform due to associated disadvantages. The ability to win an election without majority support has been the cause of much criticism of first-past-the-post by limiting the extent to which the candidate can be said to be representative of the electorate's wishes. In the 2005 General Election approximately 70% of votes cast were 'wasted', with 52% being cast in favour of losing candidates and 18% of votes were excess votes for winning candidates. This leaves 52% of those who voted with a representative they did not vote for, generating significant criticism of the system. As with most systems the employment of first-past-the-post in elections can produce an appreciable bias, in this instance towards larger parties with geographically concentrated support. The all-or-nothing nature of first-past-the-post with only one candidate being elected in each constituency creates a bias towards larger parties. Only candidates who can attain a simple majority in any constituency are elected, meaning that although a party may hold considerable support nation wide, the geographical disparity of their support can rule them out from acquiring a number of seats commensurate with their level of support. An excellent example of this is the Liberal Democrats who, despite obtaining over a fifth of the popular vote, received only a tenth of the seats in the House of Commons. A further example is the 1992 General Election in which John Major's Conservative Party received the highest number of votes in a UK General Election, but managed only a 30(?) seat majority.
Figure 1.1 compares the proportion of seats and the proportion of votes from the 2005 General Election and illustrates the disproportional distribution of seats.In addition to these criticisms it has been suggested that first-past-the-post reduces the amount and quality of electoral participation. Critics claim that the reduced incentive to vote in 'safe seats' reduces the turnout and as a result the legitimacy of the government.(pg106 Developments) The likely hood of tactical voting also increases under first-past-the-post with supporters of opponents in safe seats instead of voting for their preferred candidate voting for another with a greater chance of defeating the incumbent, an action referred to as tactical voting.
Alternative vote is a majority system, used to elect a representative for a single member constituency, under which the voter is presented with a list of candidates which they then rank in order of preferences. In order to be elected a candidate must receive a majority of votes. The first preferences of the electorate are counted and if one candidate has gained a majority of first preferences they are elected, otherwise, the candidate who received the fewest number of first preferences is eliminated and their votes are redistributed according to the voter's second preference. This continues until a candidate gains a majority and is elected.
This system tends to be more representative than fist-past-the-post with the winning candidate likely, having received a majority, got a mandate from a larger proportion of the electorate than the winner under first-past-the-post, with candidates routinely winning on less than a majority. Additionally, the link between constituency and representative is preserved providing the electorate with an easily identifiable contact by which they can address their grievances, something reduced under systems with multi-member constituencies.
Utilization of alternative vote can present a significant bias in favour of centre parties who, on the basis of their policies being the least acrimonious, are able to win on 2nd and 3rd preferences.
Single Transferable Vote
Single transferable vote is used to elect several representatives in a multi-member constituency under which candidates have to achieve a quote of votes to be elected. Voters are presented with a list of candidates who they rank in order of preference. The first preferences are then counted and if a candidate achieves the quota they are elected and the surplus votes redistributed, if, however, no candidate achieves the quota then the last placed candidate is eliminated and their votes redistributed, this continues until the prerequisite number of candidates have been elected.
This system, although not as representative as the list system, is significantly more representative than first-past-the-post or the majority systems.