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 (80)MarginalBassTasSilvia SmithALP0.03MacquarieNSWMaggie DeahmALP0.12PageNSWHarry WoodsALP0.13CanningWAGeorge GearALP0.19SwanWAKim BeazleyALP0.22DicksonQldMichael LavarchALP0.26McMillanVicBarry CunninghamALP0.40GilmoreNSWPeter KnottALP0.45DunkleyVicBob ChynowethALP0.61McEwenVicPeter CleelandALP0.69MacarthurNSWChris HavilandALP1.28LeichhardtQldPeter DoddALP1.32KingstonSAGordon BilneyALP1.45MoretonQldGarrie GibsonALP1.74RichmondNSWNeville NewellALP1.77PetrieQldGary JohnsALP2.10HerbertQldTed LindsayALP2.37RankinQldDavid BeddallALP2.67CapricorniaQldMarjorie HenzellALP2.73ParramattaNSWPaul ElliottALP3.24PatersonNSWBob HorneALP3.30BrandWAWendy FatinALP3.70MakinSAPeter DuncanALP3.70CorinellaVicAlan GriffinALP3.74LyonsTasDick AdamsALP3.78CalareNSWDavid SimmonsALP4.06Eden-MonaroNSWJim SnowALP4.28LoweNSWMary EassonALP5.01Northern TerritoryNTWarren SnowdonALP5.31JagajagaVicPeter StaplesALP5.46RobertsonNSWFrank WalkerALP5.55Melbourne PortsVicClyde HoldingALP5.85BrisbaneQldArch BevisALP5.99Fairly safePerthWAStephen SmithALP6.15LilleyQldWayne SwanALP6.22HughesNSWRobert TicknerALP6.42DobellNSWMichael LeeALP6.82CorioVicGavan O'ConnorALP7.19BowmanQldCon SciaccaALP7.42FranklinTasHarry QuickALP7.43FremantleWAJohn DawkinsALP7.79GriffithQldBen HumphreysALP7.98FordeQldMary CrawfordALP8.57BartonNSWGary PunchALP9.39CanberraACTRos KellyALP9.56KalgoorlieWAGraeme CampbellALP9.94BurkeVicNeil O'KeefeALP9.96SafeHoltVicMichael DuffyALP10.10LindsayNSWRoss FreeALP10.22BanksNSWDaryl MelhamALP10.54Port AdelaideSARod SawfordALP12.05OxleyQldLes ScottALP12.58FraserACTJohn LangmoreALP12.81HothamVicSimon CreanALP12.99GreenwayNSWRuss GormanALP13.42HunterNSWEric FitzgibbonALP13.92DenisonTasDuncan KerrALP14.44BonythonSANeal BlewettALP14.75WatsonNSWLeo McLeayALP14.84Kingsford SmithNSWLaurie BreretonALP15.24WerriwaNSWJohn KerinALP15.77NewcastleNSWAllan MorrisALP16.88CharltonNSWBob BrownALP17.10ShortlandNSWPeter MorrisALP17.33LalorVicBarry JonesALP17.35CunninghamNSWStephen MartinALP17.91CalwellVicAndrew TheophanousALP18.44ScullinVicHarry JenkinsALP18.62MaribyrnongVicAlan GriffithsALP18.72ReidNSWLaurie FergusonALP18.80ProspectNSWJanice CrosioALP19.04SydneyNSWPeter BaldwinALP19.47Very safeFowlerNSWTed GraceALP22.00BlaxlandNSWPaul KeatingALP22.10ChifleyNSWRoger PriceALP22.57GrayndlerNSWJeannette McHughALP22.81BatmanVicBrian HoweALP23.43MelbourneVicLindsay TannerALP23.74ThrosbyNSWColin HollisALP24.02GellibrandVicRalph WillisALP25.38 Opposition seats (65)MarginalBendigoVicBruce ReidLIB0.07HinklerQldPaul NevilleNAT0.22MalleeVicJohn ForrestNAT0.50 v LIBParkesNSWMichael CobbNAT0.53CowanWARichard EvansLIB0.93DeakinVicKen AldredLIB1.27AdelaideSATrish WorthLIB1.31StirlingWAEoin CameronLIB1.47HindmarshSAChris GallusLIB1.64AstonVicPeter NugentLIB1.92GreySABarry WakelinLIB2.08BallaratVicMichael RonaldsonLIB2.20La TrobeVicBob CharlesLIB2.36BraddonTasChris MilesLIB2.85ChisholmVicMichael WooldridgeLIB2.88KennedyQldBob KatterNAT2.88IsaacsVicRod AtkinsonLIB2.98BennelongNSWJohn HowardLIB3.19CookNSWDon DobieLIB3.47HumeNSWJohn SharpNAT3.70FaddenQldDavid JullLIB3.77DawsonQldRay BraithwaiteNAT3.84CowperNSWGarry NehlNAT4.06LyneNSWMark VaileNAT4.24BruceVicJulian BealeLIB5.09FlindersVicPeter ReithLIB5.19FisherQldPeter SlipperLIB5.36WentworthNSWJohn HewsonLIB5.46GoldsteinVicDavid KempLIB5.54SturtSAChristopher PyneLIB5.71CaseyVicBob HalversonLIB5.97Fairly safeCorangamiteVicStewart McArthurLIB6.97BoothbySASteele HallLIB7.80MooreWAPaul FilingLIB8.73PearceWAJudi MoylanLIB8.76McPhersonQldJohn BradfordLIB9.08MenziesVicKevin AndrewsLIB9.23WannonVicDavid HawkerLIB9.27Wide BayQldWarren TrussNAT9.71FairfaxQldAlex SomlyayLIB9.80SafeHigginsVicPeter CostelloLIB10.13New EnglandNSWIan SinclairNAT10.20WarringahNSWMichael MacKellarLIB10.26GwydirNSWJohn AndersonNAT10.27MayoSAAlexander DownerLIB10.60RyanQldJohn MooreLIB10.61MackellarNSWJim CarltonLIB11.16ForrestWAGeoff ProsserLIB11.73TangneyWADaryl WilliamsLIB11.86BerowraNSWPhilip RuddockLIB12.20MoncrieffQldKathy SullivanLIB12.41IndiVicLou LiebermanLIB12.88RiverinaNSWNoel HicksNAT12.93KooyongVicAndrew PeacockLIB14.07GroomQldBill TaylorLIB14.12CurtinWAAllan RocherLIB15.22BarkerSAIan McLachlanLIB15.97GippslandVicPeter McGauranNAT16.30WakefieldSANeil AndrewLIB16.98FarrerNSWTim FischerNAT17.43MaranoaQldBruce ScottNAT18.13MitchellNSWAlan CadmanLIB18.67Very safeMurrayVicBruce LloydNAT20.41BradfieldNSWDavid ConnollyLIB23.04O'ConnorWAWilson TuckeyLIB24.02Crossbench seats (2)North SydneyNSWTed MackIND1.84 v LIBWillsVicPhil ClearyIND2.42 v ALP
References