The single most important measure in Australian election polls is the two-party preferred vote (2PP). It captures the two central characteristics of Australian House of Representatives elections: that it is a preferential voting system, in which the flow of preferences can be crucial in determining who wins a seat; and that the crucial contest to form the next government is a two-sided battle between Labor and the Coalition.
It is usually a good, although not infallible, indicator of which party will win. In 24 of the 29 elections since the second world war, the party that has surpassed 50% of the 2PP has won. The five exceptions were 1954 (Coalition 49.3), 1961 (Coalition 49.5), 1969 (Coalition 49.8), 1990 (Labor 49.9) and 1998 (when John Howard’s 48.9 was the lowest ever winning percentage).
All five exceptions were won by the government of the day, testimony to their ability sometimes to hold onto marginal seats and defy the national trend. In the first three, another factor was a greater disproportion in electorate sizes, favouring the Coalition with smaller rural electorates.
