Dunkley byelection, page-245

Good old Antony Green...

The swing needed is 6.3%, and Labor achieved a 6.4% swing the other way to win Aston. Covering the full period since Federation, the average anti-government swing is a little under 4%.

More recently there have been 52 by-elections since the election of the Hawke government in 1983. Of those, 28 were traditional two-party contests between Labor and the Coalition, the type of contest we will see in Dunkley.

Across the 28 two-party by-elections, the average anti-government two-party preferred swing was 3.5%. It was 4.7% against Labor governments in 17 contests, and 2.3% against Coalition governments in another 11.

Of the 28 by-elections, 15 were in government held seats and 13 in seats held by an opposition party. The average swing against government in government held seats was 5.4% compared to only 1.2% in Opposition held seats.

At the eight by-elections in Labor seats during Labor governments, the average swing was 8.2% compared to 2.3% in seven similar contests during Coalition governments.

The Labor Party had an astonishingly good result in Aston, in contrast to poor first term by-election results for Labor governments led by Bob Hawke and Kevin Rudd. Under both Hawke and Rudd, Labor was further ahead in polls than the Albanese government at the time of its Aston victory.

Not that average swings are a useful measure given the wide variety of swings at by-elections. Swings are more about the time specific circumstances of a by-election and are not always comparable with an average calculated over several decades.

Larger swings than required in Dunkley afflicted the Hawke government at third term by-elections in 1988. The Adelaide and Port Adelaide by-elections, fought on the now forgotten issue of timed local calls for home phones, cost the government Adelaide and produced a double digit swing in Port Adelaide. Another double digit swing struck at the Oxley by-election later the same year. Labor’s position in all three seats was restored at the 1990 election when the Hawke government was narrowly re-elected.

Not so with the 16.2% swing that delivered a rare Liberal win in the ACT at the 1995 Canberra by-election. Labor recovered Canberra at the 1996 election, but it was a pallid highlight amidst the wreckage of the Keating government’s defeat.

Going further back in time to June 1975, the famous Bass by-election produced a Liberal gain after a 14.3% swing, accurately predicting the Labor Party’s fate under Gough Whitlam later in the year.

The biggest anti-government swing under a Coalition government was in the Brisbane seat of Ryan in March 2001. Labor won the seat after a 9.7% swing. John Howard famously described the result as not a repeat of Bass and Canberra, and the Howard government recovered Ryan and was re-elected to office at the 2001 election.

So will the by-election produce an average anti-government swing and see Labor retain Dunkley, or will we see larger swing that delivers victory to the Liberal Party?

Either way, the Dunkley by-election will set the frame for politics in the first half of 2024.
Background on Federal By-election Swings – Antony Green's Election Blog