The Coalition won the 2013 federal election with 90 of 150 lower house seats on a current 17-seat, 3.65-point

two-party A two-party system is a political party system in which two major political parties consistently dominate the political landscape. At any point in time, one of the two parties typically holds a majority in the legislature and is usually referr ...

swing, defeating the 6-year Labor government. Labor holds 55 seats while

crossbenchers A crossbencher is an independent or minor party member of some legislatures, such as the British House of Lords and the Parliament of Australia. They take their name from the crossbenches, between and perpendicular to the government and oppositi ...

hold the remaining five. The

Division of Fairfax The Division of Fairfax is an Australian Electoral Division in Queensland. Geography Since 1984, federal electoral division boundaries in Australia have been determined at redistributions by a redistribution committee appointed by the Australi ...

"House of Representatives First Division Preferences"
''Virtual Tally Room 2013'',

Australian Electoral Commission The Australian Electoral Commission (AEC) is the independent federal agency in charge of organising, conducting and supervising federal Australian elections, by-elections and referendums. Responsibilities The AEC's main responsibility is to ...

. Retrieved 30 October 2013. was the last seat to be declared. Classification of seats as marginal, fairly safe or safe is applied by the independent

using the following definition: "Where a winning party receives less than 56% of the vote, the seat is classified as 'marginal', 56–60% is classified as 'fairly safe' and more than 60% is considered 'safe'.""Division Classifications – House of Representatives - Seat Summary"
''Virtual Tally Room 2013'', Australian Electoral Commission. Retrieved 30 October 2013.

Pendulum

The

Mackerras pendulum The Mackerras pendulum was devised by the Australian psephologist Malcolm Mackerras as a way of predicting the outcome of an election contested between two major parties in a Westminster style lower house legislature such as the Australian House ...

was devised by the Australian psephologist

Malcolm Mackerras Malcolm Hugh Mackerras AO (born 26 August 1939) is an Australian psephologist and commentator and lecturer on Australian and American politics. Education and works Malcolm Mackerras was born at Turramurra in Sydney in August 1939. He is a brot ...

as a way of predicting the outcome of an election contested between two major parties in a

Westminster Westminster is an area of Central London, part of the wider City of Westminster. The area, which extends from the River Thames to Oxford Street, has many visitor attractions and historic landmarks, including the Palace of Westminster, Bu ...

style

lower house A lower house is one of two Debate chamber, chambers of a Bicameralism, bicameral legislature, the other chamber being the upper house. Despite its official position "below" the upper house, in many legislatures worldwide, the lower house has co ...

legislature such as the

Australian House of Representatives The House of Representatives is the lower house of the bicameral Parliament of Australia, the upper house being the Senate. Its composition and powers are established in Chapter I of the Constitution of Australia. The term of members of the ...

, which is composed of single-member electorates and which uses a

preferential voting {{short description, Election systems Preferential voting or preference voting (PV) may refer to different election systems or groups of election systems: * Ranked voting methods, all election methods that involve ranking candidates in order of pr ...

system such as a

Condorcet method A Condorcet method (; ) is an election method that elects the candidate who wins a majority of the vote in every head-to-head election against each of the other candidates, that is, a candidate preferred by more voters than any others, whenever ...

IRV IRV or Irv or ''variant'', may refer to: *Instant-runoff voting, a type of ranked preferential voting counting method used in single-seat elections with more than two candidates *Irvine railway station, North Ayrshire, Scotland (National Rail stat ...

. The pendulum works by lining up all of the seats held in Parliament for the

government A government is the system or group of people governing an organized community, generally a state. In the case of its broad associative definition, government normally consists of legislature, executive, and judiciary. Government is a ...

, the

opposition Opposition may refer to: Arts and media * ''Opposition'' (Altars EP), 2011 EP by Christian metalcore band Altars * The Opposition (band), a London post-punk band * ''The Opposition with Jordan Klepper'', a late-night television series on Comed ...

and the cross benches according to the

percentage-point A percentage point or percent point is the unit for the arithmetic difference between two percentages. For example, moving up from 40 percent to 44 percent is an increase of 4 percentage points, but a 10-percent increase in the quantity being me ...

margin they are held by on a two party preferred basis. This is also known as the swing required for the seat to change hands. Given a uniform swing to the opposition or government parties, the number of seats that change hands can be predicted.

References

{{2013 Australian federal election Pendulums for Australian federal elections