Swing (politics)
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An electoral swing analysis (or swing) shows the extent of change in voter support from one election to another. It is an indicator of voter support for individual candidates or political parties, or voter preference between two or more candidates or parties. A swing can be calculated for the electorate as a whole, or for a given electoral district or demographic.
A swing is particularly useful for analysing change in voter support over time, or as a tool for predicting the outcome of elections in constituency-based systems.
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[edit] Calculation
A swing is calculated by comparing the percentage of the vote in a particular election to the percentage of the vote belonging to the same party or candidate at the previous election
Percentage of vote (current election) minus percentage of vote (previous election)[clarification needed]
It can also be used in comparing a shift in voter intentions in analysing political polls.
[edit] Example
An example is the comparison between the 2006 and 2007 Ukrainian Parliamentary elections.
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The above charts show the change in voter support for each of the six major political parties by electoral district and nationwide vote results.
The data is derived from the official published election results.
[edit] Two-party swing
In some states, particularly Australia and its states and territories[citation needed], the swing is expressed in terms of two parties. This practice is most useful where a strong two-party system exists, and is used to predict the outcome of elections in constituency-based systems where different seats are held with different levels of support. Two assumptions underlie such a calculation: that a loss of support for one party is accompanied by an equivalent gain in support for the other, and that all districts will experience the same swing. Employing these two assumptions allows the analyst to compute an electoral pendulum, predicting how many (and which) seats will change hands given a particular swing, and what size uniform swing would therefore bring about a change of government.
[edit] Australia
The term "swing" has a different meaning in Australia, which uses a preferential voting system.
[edit] United Kingdom
Swing in a British political context is a single figure used as an indication of the scale of voter change between two political parties. It originated as a mathematical calculation for comparing the results of two constituencies. Britain, like the US, uses a first-past-the-post voting system. The UK uses a two party swing calculation adding one party's percent rise to the fall of the other, and then dividing the total by two. So if party one's vote rises by 4% and party two's vote falls 5%, the swing is 4.5%.(ref: http://news.bbc.co.uk/1/hi/uk_politics/vote_2005/basics/4415923.stm#swing)
[edit] United States of America
Swing in the United States can refer to swing state, those states that are known to shift in outcome between Democrats and Republican Parties. Other States are considered non-swing states, similar to the UK concept of safe seats, as they rarely change in outcome. The extent of change in political outcome is heavily influenced by the voting system in use; as in the UK, the US employs a first-past-the-post voting system.
