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.
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.
Classification of seats as marginal, fairly safe or safe is applied by the independent Australian Electoral Commission 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'."
This Mackerras pendulum includes new notional margin estimates in Victoria and Western Australia due to boundary redistributions. Members in italics have declared they will not contest their seats at the election, or have lost their party's preselection.
Government seats (76) MarginalBassTasBridget ArcherLIB0.4ChisholmVicGladys LiuLIB0.5WentworthNSWDave SharmaLIB vs. IND1.3BoothbySANicolle FlintLIB1.4BraddonTasGavin PearceLIB3.1ReidNSWFiona MartinLIB3.2LongmanQldTerry YoungLNP3.3SwanWASteve IronsLIB3.3HigginsVicKatie AllenLIB3.7LeichhardtQldWarren EntschLNP4.2RobertsonNSWLucy WicksLIB4.2CaseyVicTony SmithLIB4.6DicksonQldPeter DuttonLNP4.6DeakinVicMichael SukkarLIB4.7BrisbaneQldTrevor EvansLNP4.9LindsayNSWMelissa McIntoshLIB5.0PearceWAChristian PorterLIB5.2La TrobeVicJason WoodLIB5.5FlindersVicGreg HuntLIB5.6KooyongVicJosh FrydenbergLIB vs. GRN5.6HasluckWAKen WyattLIB5.8Fairly safeRyanQldJulian SimmondsLNP6.0BanksNSWDavid ColemanLIB6.3CowperNSWPat ConaghanNAT vs. IND6.8SturtSAJames StevensLIB6.9MonashVicRussell BroadbentLIB6.9BennelongNSWJohn AlexanderLIB6.9MenziesVicKevin AndrewsLIB7.0BonnerQldRoss VastaLNP7.4GoldsteinVicTim WilsonLIB7.8HerbertQldPhillip ThompsonLIB8.4PetrieQldLuke HowarthLNP8.4FordeQldBert Van ManenLNP8.6FlynnQldKen O'DowdLNP8.7North SydneyNSWTrent ZimmermanLIB9.3PageNSWKevin HoganNAT9.4TangneyWABen MortonLIB9.5HughesNSWCraig KellyLIB9.9SafeAstonVicAlan TudgeLIB10.1WannonVicDan TehanLIB10.2BowmanQldAndrew LamingLNP10.2FarrerNSWSussan LeyLIB vs. IND10.9CanningWAAndrew HastieLIB11.6MooreWAIan GoodenoughLIB11.6McPhersonQldKaren AndrewsLNP12.2CapricorniaQldMichelle LandryLNP12.4FisherQldAndrew WallaceLNP12.7HumeNSWAngus TaylorLIB13.0Wide BayQldLlew O'BrienLNP13.1MackellarNSWJason FalinskiLIB13.2CalareNSWAndrew GeeNAT13.3GreySARowan RamseyLIB13.3FairfaxQldTed O'BrienLNP13.4DurackWAMelissa PriceLIB13.5CurtinWACelia HammondLIB14.0FaddenQldStuart RobertLNP14.2New EnglandNSWBarnaby JoyceNAT vs. IND14.4HinklerQldKeith PittLNP14.5DawsonQldGeorge ChristensenLNP14.6ForrestWANola MarinoLIB14.6WrightQldScott BuchholzLNP14.6LyneNSWDavid GillespieNAT15.2MoncrieffQldAngie BellLNP15.4O'ConnorWARick WilsonLIB15.4BerowraNSWJulian LeeserLIB15.6MalleeVicAnne WebsterNAT15.7BradfieldNSWPaul FletcherLIB16.6GippslandVicDarren ChesterNAT16.7ParkesNSWMark CoultonNAT16.9GroomQldGarth HamiltonLNP (b/e)17.2MitchellNSWAlex HawkeLIB18.6BarkerSATony PasinLIB18.9CookNSWScott MorrisonLIB19.0RiverinaNSWMichael McCormackNAT19.5NichollsVicDamian DrumNAT20.0MaranoaQldDavid LittleproudLNP vs PHON22.5
Opposition seats (69)MarginalMacquarieNSWSusan TemplemanALP0.2Eden-MonaroNSWKristy McBainALP (b/e)0.4LilleyQldAnika WellsALP0.6CowanWAAnne AlyALP0.9CorangamiteVicLibby CokerALP1.0BlairQldShayne NeumannALP1.2DobellNSWEmma McBrideALP1.5MoretonQldGraham PerrettALP1.9GilmoreNSWFiona PhillipsALP2.6DunkleyVicPeta MurphyALP2.7GreenwayNSWMichelle RowlandALP2.8GriffithQldTerri ButlerALP2.9HunterNSWJoel FitzgibbonALP3.0SolomonNTLuke GoslingALP3.1PerthWAPatrick GormanALP3.2ParramattaNSWJulie OwensALP3.5RichmondNSWJustine ElliotALP4.1ShortlandNSWPat ConroyALP4.4PatersonNSWMeryl SwansonALP5.0LyonsTasBrian MitchellALP5.2McEwenVicRob MitchellALP5.3BurtWAMatt KeoghALP5.4LingiariNTWarren SnowdonALP5.5WerriwaNSWAnne StanleyALP5.5JagajagaVicKate ThwaitesALP5.9Fairly safeMacnamaraVicJosh BurnsALP6.1IsaacsVicMark DreyfusALP6.4OxleyQldMilton DickALP6.4RankinQldJim ChalmersALP6.4HindmarshSAMark ButlerALP6.5McMahonNSWChris BowenALP6.6BrandWAMadeleine KingALP6.7FremantleWAJosh WilsonALP6.9BruceVicJulian HillALP7.3BeanACTDavid SmithALP7.5AdelaideSASteve GeorganasALP8.2WillsVicPeter KhalilALP vs. GRN8.2MacarthurNSWMike FreelanderALP8.4Kingsford SmithNSWMatt ThistlethwaiteALP8.8HoltVicAnthony ByrneALP8.9BendigoVicLisa ChestersALP8.9BartonNSWLinda BurneyALP9.4MakinSATony ZappiaALP9.7SafeHawkeVicnew seatALP10.2BallaratVicCatherine KingALP10.3MaribyrnongVicBill ShortenALP10.3CorioVicRichard MarlesALP10.3FennerACTAndrew LeighALP10.6WhitlamNSWStephen JonesALP10.9HothamVicClare O'NeilALP11.2KingstonSAAmanda RishworthALP11.9FranklinTasJulie CollinsALP12.2ChifleyNSWEd HusicALP12.4LalorVicJoanne RyanALP12.4GellibrandVicTim WattsALP13.0CunninghamNSWSharon BirdALP13.4WatsonNSWTony BurkeALP13.5NewcastleNSWSharon ClaydonALP13.8FowlerNSWChris HayesALP14.0SpenceSANick ChampionALP14.1GortonVicBrendan O'ConnorALP14.3CooperVicGed KearneyALP vs. GRN14.6BlaxlandNSWJason ClareALP14.7GrayndlerNSWAnthony AlbaneseALP vs. GRN16.3CanberraACTAlicia PayneALP17.1FraserVicDaniel MulinoALP18.1SydneyNSWTanya PlibersekALP18.7CalwellVicMaria VamvakinouALP19.6ScullinVicAndrew GilesALP21.7Crossbench seats (6) IndiVicHelen HainesIND vs. LIB1.4MayoSARebekha SharkieCA vs. LIB5.1WarringahNSWZali SteggallIND vs. LIB7.2KennedyQldBob KatterKAP vs. LNP13.3MelbourneVicAdam BandtGRN vs. LIB21.8ClarkTasAndrew WilkieIND vs. ALP22.1
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