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 (86)MarginalFisherQldMichael LavarchALP0.5BartonNSWGary PunchALP1.0FordeQldMary CrawfordALP1.0HinklerQldBrian CourticeALP1.1HawkerSAElizabeth HarveyALP1.2PetrieQldGary JohnsALP1.4DunkleyVicBob ChynowethALP1.7BallaratVicJohn MildrenALP1.9Northern TerritoryNTWarren SnowdonALP2.2IsaacsVicDavid CharlesALP2.7StreetonVicTony LambALP2.9CowanWACarolyn JakobsenALP3.2CalareNSWDavid SimmonsALP3.3MakinSAPeter DuncanALP3.4BendigoVicJohn BrumbyALP3.5HunterNSWEric FitzgibbonALP3.6AstonVicJohn SaundersonALP3.6StirlingWARon EdwardsALP3.6St GeorgeNSWStephen DuboisALP3.7CanningWAGeorge GearALP3.8DenisonTasDuncan KerrALP3.8PhillipNSWJeannette McHughALP4.1McEwenVicPeter CleelandALP4.1McMillanVicBarry CunninghamALP4.3LeichhardtQldJohn GaylerALP4.3Eden-MonaroNSWJim SnowALP4.4BurkeVicNeil O'KeefeALP4.4RobertsonNSWBarry CohenALP4.6RankinQldDavid BeddallALP4.7HentyVicJoan ChildALP4.8KingstonSAGordon BilneyALP4.8BowmanQldCon SciaccaALP5.0HughesNSWRobert TicknerALP5.1HindmarshSAJohn ScottALP5.1MooreWAAllen BlanchardALP5.2NewcastleNSWAllan MorrisALP5.3 v INDGreySALloyd O'NeilALP5.8Fairly safeParramattaNSWJohn BrownALP6.3BrisbaneQldManfred CrossALP6.4HothamVicLewis KentALP6.5AdelaideSAChris HurfordALP6.5BrandWAWendy FatinALP6.7KalgoorlieWAGraeme CampbellALP6.7BanksNSWJohn MountfordALP6.8HerbertQldTed LindsayALP6.8PerthWARic CharlesworthALP6.8DobellNSWMichael LeeALP6.9CapricorniaQldKeith WrightALP7.0ThrosbyNSWColin HollisALP7.1MaribyrnongVicAlan GriffithsALP7.2La TrobeVicPeter MiltonALP7.3SwanWAKim BeazleyALP8.0JagajagaVicPeter StaplesALP8.2LilleyQldElaine DarlingALP8.2BlaxlandNSWPaul KeatingALP8.8MacarthurNSWStephen MartinALP8.9LindsayNSWRoss FreeALP9.0GrayndlerNSWLeo McLeayALP9.7GreenwayNSWRuss GormanALP9.9Melbourne PortsVicClyde HoldingALP9.9SafeHoltVicMichael DuffyALP10.4GriffithQldBen HumphreysALP10.4ShortlandNSWPeter MorrisALP11.1ReidNSWTom UrenALP11.8CanberraACTRos KellyALP12.0FowlerNSWTed GraceALP12.4FremantleWAJohn DawkinsALP12.7CorioVicGordon ScholesALP12.9WerriwaNSWJohn KerinALP13.7ProspectNSWDick KlugmanALP13.9Kingsford SmithNSWLionel BowenALP14.2CunninghamNSWStewart WestALP14.4FraserACTJohn LangmoreALP14.5OxleyQldBill HaydenALP14.9Port AdelaideSAMick YoungALP16.3CharltonNSWBob BrownALP16.9BonythonSANeal BlewittALP18.1CalwellVicAndrew TheophanousALP18.6ChifleyNSWRoger PriceALP19.1MelbourneVicGerry HandALP19.4LalorVicBarry JonesALP19.5SydneyNSWPeter BaldwinALP19.9WillsVicBob HawkeALP19.9Very safeGellibrandVicRalph WillisALP20.6BatmanVicBrian HoweALP22.8ScullinVicHarry JenkinsALP23.2 Liberal seats (43)MarginalChisholmVicMichael WooldridgeLIB0.7MoretonQldDon CameronLIB0.7CaseyVicBob HalversonLIB1.2FlindersVicPeter ReithLIB1.3DeakinVicJulian BealeLIB1.5LoweNSWBob WoodsLIB1.6BruceVicKen AldredLIB2.0ForrestWAGeoff ProsserLIB3.1FranklinTasBruce GoodluckLIB3.3BassTasWarwick SmithLIB3.7FaddenQldDavid JullLIB4.4LyonsTasMax BurrLIB4.4CorangamiteVicStewart McArthurLIB4.6MacquarieNSWAlasdair WebsterLIB5.8Fairly safeCookNSWDon DobieLIB6.1SturtSAIan WilsonLIB6.6MenziesVicNeil BrownLIB7.3TangneyWAPeter ShackLIB7.4HumeNSWWal FifeLIB7.5BraddonTasChris MilesLIB7.9WentworthNSWJohn HewsonLIB8.0RyanQldJohn MooreLIB8.9GoldsteinVicIan MacpheeLIB9.5SafeMoncrieffQldKathy SullivanLIB10.2BennelongNSWJohn HowardLIB10.6DundasNSWPhillip RuddockLIB11.0CurtinWAAllan RocherLIB11.6BarkerSAJames PorterLIB11.6BoothbySASteele HallLIB11.6HigginsVicRoger ShiptonLIB12.6IndiVicEwen CameronLIB12.6McPhersonQldPeter WhiteLIB12.6MayoSAAlexander DownerLIB12.6WannonVicDavid HawkerLIB13.1MackellarNSWJim CarltonLIB13.2WakefieldSANeil AndrewLIB13.7KooyongVicAndrew PeacockLIB14.0WarringahNSWMichael MacKellarLIB14.1North SydneyNSWJohn SpenderLIB14.2BerowraNSWHarry EdwardsLIB16.7Very safeO'ConnorWAWilson TuckeyLIB20.6MitchellNSWAlan CadmanLIB22.5BradfieldNSWDavid ConnollyLIB26.1 National seats (19)DawsonQldRay BraithwaiteNAT1.9KennedyQldBob Katter Sr.NAT3.0Riverina-DarlingNSWNoel HicksNAT3.5PageNSWIan RobinsonNAT4.5GilmoreNSWJohn SharpNAT6.2RichmondNSWCharles BluntNAT6.6FairfaxQldEvan AdermannNAT7.3New EnglandNSWIan SinclairNAT8.4Wide BayQldClarrie MillarNAT8.8CowperNSWGarry NehlNAT9.1LyneNSWBruce CowanNAT9.8GwydirNSWRalph HuntNAT10.3ParkesNSWMichael CobbNAT10.8GroomQldTom McVeighNAT12.8MaranoaQldIan CameronNAT14.9GippslandVicPeter McGauranNAT15.0FarrerNSWTim FischerNAT15.2MalleeVicPeter FisherNAT20.1MurrayVicBruce LloydNAT20.4

References