Electoral system

An electoral system is a set of rules that determine how elections and referendums are conducted and how their results are determined. Political electoral systems are organized by governments, while non-political elections may take place in business, non-profit organisations and informal organisations. An electoral system is a set of rules that determine how elections and referendums are conducted and how their results are determined. Political electoral systems are organized by governments, while non-political elections may take place in business, non-profit organisations and informal organisations. Electoral systems consist of sets of rules that govern all aspects of the voting process: when elections occur, who is allowed to vote, who can stand as a candidate, how ballots are marked and cast, how the ballots are counted (electoral method), limits on campaign spending, and other factors that can affect the outcome. Political electoral systems are defined by constitutions and electoral laws, are typically conducted by election commissions, and can use multiple types of elections for different offices. Some electoral systems elect a single winner to a unique position, such as prime minister, president or governor, while others elect multiple winners, such as members of parliament or boards of directors. There are a large number of variations in electoral systems, but the most common systems are first-past-the-post voting, the two-round (runoff) system, proportional representation and ranked or preferential voting. Some electoral systems, such as mixed systems, attempt to combine the benefits of non-proportional and proportional systems. The study of formally defined electoral methods is called social choice theory or voting theory, and this study can take place within the field of political science, economics, or mathematics, and specifically within the subfields of game theory and mechanism design. Impossibility proofs such as Arrow's impossibility theorem demonstrates that when voters have three or more alternatives, it is not possible to design a ranked voting electoral system that reflects the preferences of individuals in a global preference of the community, present in countries with proportional representation and plurality voting. Plurality voting is a system in which the candidate(s) with the highest number of vote wins, with no requirement to get a majority of votes. In cases where there is a single position to be filled, it is known as first-past-the-post; this is the second most common electoral system for national legislatures, with 58 countries using it to elect their legislatures, the vast majority of which are current or former British or American colonies or territories. It is also the second most common system used for presidential elections, being used in 19 countries. In cases where there are multiple positions to be elected, most commonly in cases of multi-member constituencies, plurality voting is referred to as bloc voting or plurality-at-large. This takes two main forms; in one form voters have as many votes as there are seats and can vote for any candidate, regardless of party – this is used in eight countries. There are variations on this system such as limited voting, where voters are given fewer votes than there are seats to be elected (Gibraltar is the only territory where this system is in use) and single non-transferable vote (SNTV), in which voters are only able to vote for one candidate in a multi-member constituency, with the candidates receiving the most votes declared the winners; this system is used in Afghanistan, Kuwait, the Pitcairn Islands and Vanuatu. In the other main form of bloc voting, also known as party bloc voting, voters can only vote for the multiple candidates of a single party. This is used in five countries as part of mixed systems. The Dowdall system, a multi-member constituency variation on the Borda count, is used in Nauru for parliamentary elections and sees voters rank the candidates depending on how many seats there are in their constituency. First preference votes are counted as whole numbers; the second preference votes divided by two, third preferences by three; this continues to the lowest possible ranking. The sums achieved by each candidate are then totalled to determine the winner. Majoritarian voting is a system in which candidates have to receive a majority of the votes to be elected, although in some cases only a plurality is required in the last round of counting if no candidate can achieve a majority. There are two main forms of majoritarian systems, one using a single round of ranked voting and the other using two or more rounds. Both are primarily used for single-member constituencies. Majoritarian voting can take place in a single round using instant-runoff voting (IRV), whereby voters rank candidates in order of preference; this system is used for parliamentary elections in Australia and Papua New Guinea. If no candidate receives a majority of the vote in the first round, the second preferences of the lowest-ranked candidate are then added to the totals. This is repeated until a candidate achieves over 50% of the number of valid votes. If not all voters use all their preference votes, then the count may continue until two candidates remain, at which point the winner is the one with the most votes. A modified form of IRV is the contingent vote where voters do not rank all candidates, but have a limited number of preference votes. If no candidate has a majority in the first round, all candidates are excluded except the top two, with the highest remaining preference votes from the votes for the excluded candidates then added to the totals to determine the winner. This system is used in Sri Lankan presidential elections, with voters allowed to give three preferences.