Pre-election pendulum for the 2026 South Australian state election

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 South Australian House of Assembly, 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.

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'."

Pendulum A redistribution, required after each election, was finalised by the South Australian Electoral Districts Boundaries Commission in December 2024. The below post-redistribution pendulum shows all seats by their redistributed notional margin, taking into account by-elections and defections.

Italics indicate that the incumbent member is retiring, switching to another seat or the seat is vacant.

Labor seats (29)MarginalDunstanCressida O'HanlonALP0.8GibsonSarah AndrewsALP2.5DavenportErin ThompsonALP3.4KingRhiannon PearceALP4.0WaiteCatherine HutchessonALP4.0NewlandOlivia SavvasALP5.4ElderNadia ClancyALP5.6Fairly safeAdelaideLucy HoodALP6.2BlackAlex Dighton ALP9.9 SafeTorrensDana WortleyALP10.0LeeStephen MullighanALP11.5WrightBlair BoyerALP11.9FloreyMichael BrownALP12.8MawsonLeon BignellALP13.8EnfieldAndrea MichaelsALP14.5BadcoeJayne StinsonALP14.8Hurtle ValeNat CookALP15.7PlayfordJohn FulbrookALP16.3ReynellKatrine HildyardALP17.2TaylorNick ChampionALP18.4West TorrensTom KoutsantonisALP18.8CheltenhamJoe SzakacsALP19.1GilesEddie HughesALP19.7KaurnaChris PictonALP19.8RamsayZoe BettisonALP19.9Very safeLightTony Piccolo ALP20.1ElizabethLee OdenwalderALP21.7Port AdelaideSusan CloseALP21.8CroydonPeter MalinauskasALP24.8Liberal seats (16) MarginalFinnissDavid BashamLIB0.7 v INDMorialtaJohn GardnerLIB1.4UnleyDavid PisoniLIB2.2HeysenJosh TeagueLIB2.6FlindersSam TelferLIB3.0 v INDNgadjuriPenny PrattLIB3.2KavelDan Cregan(IND)LIB3.5HartleyVincent TarziaLIB3.6MorphettStephen PattersonLIB4.5ColtonMatt CowdreyLIB4.8HammondAdrian PederickLIB5.1Fairly safeBraggJack BattyLIB8.2SafeSchubertAshton HurnLIB11.9Mt Gambier Troy Bell (IND) LIB13.8ChaffeyTim WhetstoneLIB17.2Very safeMacKillopNick McBride (IND) LIB22.6 Crossbench seats (2)NarunggaFraser EllisIND8.1 v LIBStuartGeoff BrockIND14.1 v LIB

Notes

References