Post-election pendulum for the 1998 Australian federal election

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The Mackerras pendulum 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 of Representatives, which is composed of single-member electorates and which uses a preferential voting system such as a Condorcet method or instant-runoff voting.

The pendulum works by lining up all of the seats held in Parliament for the government, the opposition and the crossbenches according to the percentage point 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. [1]

Government seats (80)
Marginal
Herbert Qld Peter Lindsay LIB0.10
Eden-Monaro NSW Gary Nairn LIB0.18
Hinkler Qld Paul Neville NAT0.34
Moreton Qld Gary Hardgrave LIB0.57
Petrie Qld Teresa Gambaro LIB0.75
Richmond NSW Larry Anthony NAT0.77
Adelaide SA Trish Worth LIB0.91
Longman Qld Mal Brough LIB0.92
Makin SA Trish Draper LIB0.94
La Trobe Vic Bob Charles LIB0.99
McEwen Vic Fran Bailey LIB1.04
Parramatta NSW Ross Cameron LIB1.07
Hindmarsh SA Chris Gallus LIB1.23
Lindsay NSW Jackie Kelly LIB1.28
Mayo SA Alexander Downer LIB1.74 v DEM
Deakin Vic Phil Barresi LIB1.93
Robertson NSW Jim Lloyd LIB2.01
Dunkley Vic Bruce Billson LIB2.04
Kalgoorlie WA Barry Haase LIB2.10
Page NSW Ian Causley NAT2.36
Ballarat Vic Michael Ronaldson LIB2.77
Wide Bay Qld Warren Truss NAT2.86
Blair Qld Cameron Thompson LIB3.40 v ONP
Flinders Vic Peter Reith LIB3.72
Gilmore NSW Joanna Gash LIB4.04
Leichhardt Qld Warren Entsch LIB4.05
Macquarie NSW Kerry Bartlett LIB4.10
Parkes NSW Tony Lawler NAT4.11
Aston Vic Peter Nugent LIB4.24
Fairfax Qld Alex Somlyay LIB4.36
Dawson Qld De-Anne Kelly NAT4.42
Corangamite Vic Stewart McArthur LIB4.50
Casey Vic Michael Wooldridge LIB4.87
Forde Qld Kay Elson LIB5.25
Pearce WA Judi Moylan LIB5.30
Menzies Vic Kevin Andrews LIB5.40
Hughes NSW Danna Vale LIB5.52
Macarthur NSW John Fahey LIB5.63
Tangney WA Daryl Williams LIB5.90
Fairly safe
Bennelong NSW John Howard LIB6.03
Moore WA Mal Washer LIB6.04
Wentworth NSW Andrew Thomson LIB6.32
Cowper NSW Garry Nehl NAT6.36
Forrest WA Geoff Prosser LIB6.88
Sturt SA Christopher Pyne LIB7.29
Wannon Vic David Hawker LIB7.44
Boothby SA Andrew Southcott LIB7.45
Fadden Qld David Jull LIB7.59
Grey SA Barry Wakelin LIB8.04
Hume NSW Alby Schultz LIB8.06
Goldstein Vic David Kemp LIB8.15
McPherson Qld Margaret May LIB8.34
Gippsland Vic Peter McGauran NAT8.83
Cook NSW Bruce Baird LIB8.94
Ryan Qld John Moore LIB9.52
Higgins Vic Peter Costello LIB9.62
Lyne NSW Mark Vaile NAT9.72
Safe
Indi Vic Lou Lieberman LIB10.11
Fisher Qld Peter Slipper LIB11.00
Kennedy Qld Bob Katter NAT11.19
Kooyong Vic Petro Georgiou LIB11.39
North Sydney NSW Joe Hockey LIB12.22
Moncrieff Qld Kathy Sullivan LIB12.83
New England NSW Stuart St. Clair NAT12.93
Warringah NSW Tony Abbott LIB12.93
Groom Qld Ian Macfarlane LIB13.04
Curtin WA Julie Bishop LIB13.28
Berowra NSW Philip Ruddock LIB13.52
Gwydir NSW John Anderson NAT13.58
Barker SA Patrick Secker LIB13.74
Maranoa Qld Bruce Scott NAT14.42
Farrer NSW Tim Fischer NAT14.62
O'Connor WA Wilson Tuckey LIB15.14
Riverina NSW Kay Hull NAT15.30
Mackellar NSW Bronwyn Bishop LIB15.64
Wakefield SA Neil Andrew LIB16.26
Mallee Vic John Forrest NAT19.37
Mitchell NSW Alan Cadman LIB19.85
Very safe
Murray Vic Sharman Stone LIB22.06
Bradfield NSW Brendan Nelson LIB23.20
Opposition seats (67)
Marginal
Bass Tas Michelle O'Byrne ALP0.06
Dickson Qld Cheryl Kernot ALP0.12
Kingston SA David Cox ALP0.47
Northern Territory NT Warren Snowdon ALP0.57
McMillan Vic Christian Zahra ALP0.57
Stirling WA Jann McFarlane ALP1.04
Paterson NSW Bob Horne ALP1.22
Chisholm Vic Anna Burke ALP2.07
Griffith Qld Kevin Rudd ALP2.43
Swan WA Kim Wilkie ALP2.70
Lilley Qld Wayne Swan ALP3.13
Bowman Qld Con Sciacca ALP3.29
Dobell NSW Michael Lee ALP3.35
Bendigo Vic Steve Gibbons ALP3.47
Canning WA Jane Gerick ALP3.52
Cowan WA Graham Edwards ALP3.56
Braddon Tas Sid Sidebottom ALP4.33
Brisbane Qld Arch Bevis ALP4.59
Lowe NSW John Murphy ALP4.63
Capricornia Qld Kirsten Livermore ALP5.29
Melbourne Ports Vic Michael Danby ALP5.83
Jagajaga Vic Jenny Macklin ALP5.91
Fairly safe
Isaacs Vic Greg Wilton ALP6.40
Franklin Tas Harry Quick ALP6.60
Bruce Vic Alan Griffin ALP6.72
Bank NSW Daryl Melham ALP7.11
Burke Vic Neil O'Keefe ALP7.61
Oxley Qld Bernie Ripoll ALP8.20
Rankin Qld Craig Emerson ALP8.69
Barton NSW Robert McClelland ALP9.76
Greenway NSW Frank Mossfield ALP9.94
Safe
Fremantle WA Carmen Lawrence ALP10.02
Canberra ACT Annette Ellis ALP10.06
Lyons Tas Dick Adams ALP10.61
Corio Vic Gavan O'Connor ALP11.36
Brand WA Kim Beazley ALP12.29
Werriwa NSW Mark Latham ALP12.67
Shortland NSW Jill Hall ALP12.81
Charlton NSW Kelly Hoare ALP12.97
Perth WA Stephen Smith ALP13.28
Kingsford Smith NSW Laurie Brereton ALP13.40
Hotham Vic Simon Crean ALP13.56
Denison Tas Duncan Kerr ALP14.51
Bonython SA Martyn Evans ALP14.53
Hunter NSW Joel Fitzgibbon ALP14.69
Fraser ACT Bob McMullan ALP14.86
Holt Vic Anthony Byrne ALP15.11
Port Adelaide SA Rod Sawford ALP16.10
Sydney NSW Tanya Plibersek ALP16.89
Newcastle NSW Allan Morris ALP17.33 v GRN [lower-alpha 1]
Watson NSW Leo McLeay ALP17.47
Cunningham NSW Stephen Martin ALP18.20
Calwell Vic Andrew Theophanous ALP18.98
Prospect NSW Janice Crosio ALP19.71
Lalor Vic Julia Gillard ALP19.82
Very safe
Chifley NSW Roger Price ALP20.89
Wills Vic Kelvin Thomson ALP20.96
Reid NSW Laurie Ferguson ALP21.64
Melbourne Vic Lindsay Tanner ALP21.80
Scullin Vic Harry Jenkins ALP21.84
Blaxland NSW Michael Hatton ALP22.06
Maribyrnong Vic Bob Sercombe ALP22.06
Grayndler NSW Anthony Albanese ALP22.32
Throsby NSW Colin Hollis ALP22.46
Gellibrand Vic Nicola Roxon ALP25.91
Fowler NSW Julia Irwin ALP26.33
Batman Vic Martin Ferguson ALP26.43
Crossbench seats (1)
Calare NSW Peter Andren IND22.31 v ALP

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The following is a pendulum based on the outcome of the 2010 federal election and changes since, including the redistributions of seats in South Australia and Victoria. It is a Mackerras pendulum, invented by psephologist Malcolm Mackerras, which works by lining up all of the seats held in Parliament according to the percentage point margin on a two-candidate-preferred basis. The two-party result is also known as the swing required for the seat to change hands. Given a uniform swing to the opposition or government parties in an election, the number of seats that change hands can be predicted. Swings are never uniform, but in practice variations of swing among the Australian states usually tend to cancel each other out. Seats are arranged in safeness categories according to the Australian Electoral Commission's (AEC) classification of safeness. "Safe" seats require a swing of over 10 per cent to change, "fairly safe" seats require a swing of between 6 and 10 per cent, while "marginal" seats require a swing of less than 6 per cent. The swings for South Australian and Victorian seats are notional, based on calculations by the AEC.

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This is a Mackerras pendulum for the 2016 Australian federal election.

The Coalition won the 2016 federal election with a one-seat majority 76 of 150 lower house seats. Labor holds 69 seats while crossbenchers hold the remaining five.

The Labor party won the 2018 state election by winning 55 of the 88 lower house seats. The coalition won 27 seats while the Greens and independents won 3 each.

The Coalition won the 2019 federal election with a three-seat majority of 77 of 151 lower house seats. Labor holds 68 seats, and crossbenchers hold the remaining six.

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 of Representatives, which is composed of single-member electorates and which uses a preferential voting system such as a Condorcet method or IRV.

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The Mackerras pendulum 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 of Representatives, which is composed of single-member electorates and which uses a preferential voting system such as a Condorcet method or instant-runoff voting.

The Mackerras pendulum 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 of Representatives, which is composed of single-member electorates and which uses a preferential voting system such as a Condorcet method or instant-runoff voting.

The Mackerras pendulum 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 of Representatives, which is composed of single-member electorates and which uses a preferential voting system such as a Condorcet method or instant-runoff voting.

References

  1. Sakkal, Paul; Rooney, Kieran (14 November 2023). "Veteran Liberal Party MP Russell Broadbent quits party, moves to crossbench". The Sydney Morning Herald.