Your digital subscription includes access to content from all our websites in your region. Access unlimited content, as well as The Canberra Times app.

Across Australia's 151 voter electorates, four have been given the status of "bellwether".

A bellwether seat is an electoral division that consistently votes in a local member from the party that ends up forming government.

For political scientists and polling pundits, the bellwethers gauge the temperature of the nation. These four seats are often where the two major parties will devote a lot of attention during the election campaign.

Three of the seats - Robertson, Lindsay, and Eden-Monaro - are in NSW, while the fourth seat - Makin - is in South Australia.

At a national level, the whole state of NSW can be considered a bellwether.

Until the 2016 election, the state's government had been the same at each election to the party that formed a majority in the federal House of Representatives.

Of the four bellwether seats, Robertson on the NSW Central Coast (north of Sydney) has been the longest-held bellwether.

Robertson has been held by the party that's formed government every election since 1983.

It is currently a Liberal seat with member Lucy Wicks seeking re-election again this weekend.

Wicks has held the seat since 2013, the same year Liberal's Tony Abbott was elected prime minister.

Although, opinion polls ahead of this weekend's election suggest Wicks' hopes for re-election may be in jeopardy.

By contrast, Eden-Monaro in NSW was a consistent bellwether seat from 1972 until 2016. Its record was broken after Labor won the seat while the Coalition formed government.

Lindsay in NSW was a bellwether from its creation in 1984 before it too broke the trend in 2016.

Makin lost its official status as a bellwether in 2013 after previously following the trend since 1984.

That year, the South Australian seat voted to stay with Labor despite the Coalition re-gaining power nationally.

So how do these seats keep consistently predicting the government?

Dr Jacob Deem from the University of Central Queensland says there is a lot of chance involved in this. The seats tend to be marginal seats that just happen to swing with the government of the day.

"A marginal seat is any seat that is held by less than six percent of a majority," Dr Deem said.

"Most bellwether seats are marginal as well, but a marginal seat can have sided with the Opposition.

"So for example, a seat that voted for a Labor candidate while there's a Coalition government that would be marginal but not a bellwether because it didn't side with the party that formed government.

"Most bellwether seats are marginal seats, but not always. But not all marginal seats are bellwether seats."

National videographer, filmmaker, and editor. Former features and weekender writer for The Daily Advertiser. Small, quiet, and a student of the Julie Bishop School Of Staring. Usually dressed in something colourful, always snacking on something homemade. Friend to most mothers and all dogs. Got stories? Get in touch. emma.horn@austcommunitymedia.com.au

National videographer, filmmaker, and editor. Former features and weekender writer for The Daily Advertiser. Small, quiet, and a student of the Julie Bishop School Of Staring. Usually dressed in something colourful, always snacking on something homemade. Friend to most mothers and all dogs. Got stories? Get in touch. emma.horn@austcommunitymedia.com.au

Sign up for our newsletter to stay up to date.

We care about the protection of your data. Read our Privacy Policy.