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.
Government seats (75)MarginalDiamond ValleyVicPeter StaplesALP0.2PetrieQldDeane WellsALP0.5CaseyVicPeter SteedmanALP0.7FlindersVicBob ChynowethALP1.0Eden-MonaroNSWJim SnowALP1.6FaddenQldDavid BeddallALP1.7PhillipNSWJeannette McHughALP1.9Northern TerritoryNTJohn ReevesALP1.9MacarthurNSWColin HollisALP2.1DeakinVicJohn SaundersonALP2.1LeichhardtQldJohn GaylerALP2.1BartonNSWGary PunchALP2.2ChisholmVicHelen MayerALP2.2BowmanQldLen KeoghALP2.2BendigoVicJohn BrumbyALP2.8HerbertQldTed LindsayALP2.8CalareNSWDavid SimmonsALP3.0McMillanVicBarry CunninghamALP3.1KingstonSAGordon BilneyALP3.1TangneyWAGeorge GearALP3.2BallaratVicJohn MildrenALP4.1LoweNSWMichael MaherALP5.9Fairly safeGreySALloyd O'NeilALP6.1PerthWARic CharlesworthALP6.4BrisbaneQldManfred CrossALP6.9StirlingWARon EdwardsALP7.0MooreWAAllen BlanchardALP7.2HawkerSARalph JacobiALP7.3CanningWAWendy FatinALP7.4HentyVicJoan ChildALP7.5IsaacsVicDavid CharlesALP9.0LilleyQldElaine DarlingALP9.2RobertsonNSWBarry CohenALP9.3KalgoorlieWAGraeme CampbellALP9.5CapricorniaQldDoug EveringhamALP9.9HindmarshSAJohn ScottALP10.0SafeHothamVicLewis KentALP10.1St GeorgeNSWBill MorrisonALP10.5La TrobeVicPeter MiltonALP10.9BanksNSWJohn MountfordALP11.1MacquarieNSWRoss FreeALP11.8HoltVicMichael DuffyALP12.6AdelaideSAChris HurfordALP12.6CorioVicGordon ScholesALP13.0GrayndlerNSWLeo McLeayALP13.2MaribyrnongVicAlan GriffithsALP13.8CanberraACTRos KellyALP13.9Melbourne PortsVicClyde HoldingALP14.1GriffithQldBen HumphreysALP14.5BlaxlandNSWPaul KeatingALP15.0ProspectNSWDick KlugmanALP15.2BurkeVicAndrew TheophanousALP15.5BonythonSANeal BlewettALP15.8SwanWAKim BeazleyALP16.2FremantleWAJohn DawkinsALP16.5ParramattaNSWJohn BrownALP17.2NewcastleNSWAllan MorrisALP17.5ReidNSWTom UrenALP17.6FraserACTKen FryALP18.0HughesNSWLes JohnsonALP18.3CunninghamNSWStewart WestALP18.6WerriwaNSWJohn KerinALP19.1Very safeMelbourneVicGerry HandALP20.2OxleyQldBill HaydenALP20.7ShortlandNSWPeter MorrisALP20.8LalorVicBarry JonesALP21.8ChifleyNSWRuss GormanALP22.4HunterNSWBob BrownALP22.6ScullinVicHarry Jenkins, Sr.ALP22.6Kingsford SmithNSWLionel BowenALP23.5WillsVicBob HawkeALP24.1Port AdelaideSAMick YoungALP24.2SydneyNSWPeter BaldwinALP25.7GellibrandVicRalph WillisALP25.9BatmanVicBrian HoweALP27.1 Opposition seats (50)MarginalCookNSWDon DobieLIB0.1RiverinaNSWNoel HicksNAT0.4BruceVicBilly SneddenLIB0.7DawsonQldRay BraithwaiteNAT1.2ForrestWAPeter DrummondLIB1.4MoretonQldJames KillenLIB1.6Wide BayQldClarrie MillarNAT1.9SturtSAIan WilsonLIB2.0CowperNSWIan RobinsonNAT2.1DundasNSWPhilip RuddockLIB2.7New EnglandNSWIan SinclairNAT2.7BalaclavaVicIan MacpheeLIB3.4FranklinTasBruce GoodluckLIB3.5CurtinWAAllan RocherLIB4.5WilmotTasMax BurrLIB5.1LyneNSWBruce CowanNAT5.3BennelongNSWJohn HowardLIB5.7DenisonTasMichael HodgmanLIB5.8PatersonNSWFrank O'KeefeNAT5.9RichmondNSWDoug AnthonyNAT5.9Fairly safeHumeNSWStephen LusherNAT6.8FisherQldEvan AdermannNAT7.1RyanQldJohn MooreLIB7.5HigginsVicRoger ShiptonLIB8.0CorangamiteVicTony StreetLIB8.2BassTasKevin NewmanLIB8.3MackellarNSWJim CarltonLIB8.3GwydirNSWRalph HuntNAT8.8KooyongVicAndrew PeacockLIB9.1KennedyQldBob Katter, Sr.NAT9.1FarrerNSWWal FifeLIB9.2GippslandVicPeter McGauranNAT9.7WannonVicMalcolm FraserLIB9.7SafeBoothbySASteele HallLIB10.1WarringahNSWMichael MacKellarLIB10.2McPhersonQldPeter WhiteLIB10.3North SydneyNSWJohn SpenderLIB10.4MitchellNSWAlan CadmanLIB10.5IndiVicEwen CameronLIB10.6WentworthNSWPeter ColemanLIB12.4BraddonTasRay GroomLIB12.6WakefieldSANeil AndrewLIB13.7BarkerSAJames PorterLIB13.8BerowraNSWHarry EdwardsLIB13.9Darling DownsQldTom McVeighNAT14.0O'ConnorWAWilson TuckeyLIB14.1MaranoaQldIan CameronNAT16.2Very safeMurrayVicBruce LloydNAT21.3MalleeVicPeter FisherNAT22.0BradfieldNSWDavid ConnollyLIB24.7
References