Swing (politics)

This article is about the political term. For other uses, see Swing (disambiguation).

An electoral swing analysis (or swing) shows the extent of change in voter support, typically from one election to another, expressed as a positive or negative percentage. A multi-party swing is an indicator of a change in the electorate's preference between candidates or parties (e.g. Conservative to Social Democrat). A swing can be calculated for the electorate as a whole, for a given electoral district or for a particular 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. Swing is also usefully deployed when analysing the shift in voter intentions revealed by (political) opinion polls or to compare polls concisely which may rely on differing samples and on markedly different swings and therefore predict extraneous results.

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.

One Party Swing = Percentage of vote (current election) − percentage of vote (previous election).

Example

Examples include the comparison between the 2006 and 2007 Ukrainian Parliamentary elections and the win of AAP in the 2015 Delhi elections.

Swing Analysis comparison Ukrainian Parliamentary Elections 2006 to 2007:

The above charts show the change in voter support for each of the six major political parties by electoral district and nationwide vote results.

Two-party swing

In many nation states media, including Australia and in the United Kingdom swing is normally expressed in terms of two parties. This practice is most useful where most governments tend to be from an existing two-party system but other candidates do sometimes run, and is used to predict the outcome of elections in constituency-based systems where different seats are held with different previous levels of support. An assumption underlies extrapolated national calculations: that all districts will experience the same swing as shown in a poll or in a place's results. The advantage of this swing is the fact that the loss of support for one party will in most cases be accompanied by smaller or bigger gain in support for the other, but both figures are averaged into one. Employing the 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.

Australia

Main article: Swing (Australian politics)

The term "swing" makes reference in Australia, to wit in the preferential voting system, to the change in the outcome of an election from the viewpoint of specific political parties.

United Kingdom

Main article: Swing (United Kingdom)

The UK uses the two party swing (averaged model), adding one party's increase in share of the vote (expressed as a percentage) to the percentage fall of another party and 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% (Party 2 to Party 1). For disambiguation suffixes such as: (Con to Lab) (Lab to Lib Dem) (Lib Dem to Con) must be added where three parties stand. Otherwise a problem when deciding which swing is meant and which swing is best to publish arises where a lower party takes first or second; or where a party loses one of the top two places.

Originating as a mathematical calculation for comparing the results of two constituencies, any of these figures can be used as an indication of the scale of voter change between any two political parties, as shown below for the 2010 United Kingdom general election:

• 

  Labour to Conservative swing

• 

  Liberal Democrat to Conservative swing

• 

  Labour to Liberal Democrat swing

United States of America

Main article: Swing state

Swing in the United States can refer to swing state, those states that are known to shift in outcome between Democrats and Republican Parties, equivalent on a local level to marginal seats. By contrast, a non-swing state is the direct equivalent of a safe seat, as they rarely change in outcome. The extent of change in political outcome is heavily influenced by the voting system in use.

Three Party Swing or Greater

Some websites provide a pie chart based or column-based multi party swingometer where ± x%, ± x%, ± x% and so on is displayed or can be input for three parties (or more in more plural democracies). This tool or illustration provides likely outcomes wherever more than two political parties have a significant influence on which politicians are elected.

Notes and References

Notes

References

See also

• Swing vote
• Swingometer

• Electoral Calculus 2010 Election: UK Polls Comparison
• Ukraine - official published election results
• Electoral Calculus website
• BBC Swingometer
• UK Polling Report Swingometer Map
• BBC Explanation of Two Way Swing
• Guardian Swingometer