Seats Projection

Methodology

This projection is based on estimates of three-party preferred vote shares for Labor, the Coalition and One Nation, starting from a Dirichlet model trained on results from the South Australian election in March in which the predictor variables are equivalent Senate results from the 2025 federal election, the yes vote from the 2023 Indigenous Voice referendum (which associates negatively with the One Nation vote), the rate of outright home ownership (associated with the Liberal vote) and a dummy variable for seats defended by a Coalition incumbent (where the Liberal vote held up better against One Nation).

This produces a base set of results for which the means are ALP 39.9%, L-NP 32.8% and ON 27.3%, which are adjusted to accord with a statewide estimate of three-party preferred based on the current reading of BludgerTrack. These adjustments are proportional to each party's base modelled vote share relative to its rivals, so that a party loses more in seats where it has more to lose and less where its vote is already low (and can never fall below zero).

In addition to the three-party estimates, two-party preferred estimates are determined for each of the three possible two-party pairs by applying estimated preference flows from the excluded party. The party that leads on the two-party pairing deemed most likely by the three-party estimate is determined to be the likely winner. This result is designated as “solid” if the likely winner has a margin of over 4% on all two-party pairings allowed as possibilities by the three-party estimate, which likewise requires margins greater than 4%, and otherwise as “lean”.

The three-party model does not encompass the Greens, but accommodates them to the extent of substituting the Greens for Labor in the four seats the party won in 2022, namely Melbourne, Brunswick, Richmond and Prahran. This means it does not allow for the possibility of them losing any of these seats to Labor, or gaining others. For the Coalition, each seat is designated either as a contest involving Liberal or the Nationals, with no allowance for three-cornered contests. The Nationals-designated seats are the nine the party won in 2022 plus Bendigo East and Bendigo West.