Australians are becoming more polarised in their political beliefs as Labor, Greens and informal voters move to the left while Liberal voters stay put and National voters move to the right.



Inspired by Pew Research’s look at political polarisation in the US, we’ve crunched the numbers on Australian voters using the Australian Electoral Study survey (AES).

Since 1996 the AES has asked voters to place themselves on an ideological scale from 0 to 10 with 0 being left, 10 right and 5 being the middle. The mean is the average position for a given group. The standard deviation (SD) from the mean reflects the variation or dispersion from the average. The lower the standard deviation, the closer data points tend to be to the mean, and higher means people’s political views are spread further out along the scale.

So, using the standard deviation as a measure of polarisation, we can see it has increased over time:

Photograph: Graph

On the whole, Australians have become more left wing as the average voter has moved from 5.47 to 5.15 on the political position scale between 1996 and 2013:

Photograph: Graph

The AES survey records how people surveyed voted at the previous election. From this we can see that the polarisation trend has largely been driven by Labor, Greens and informal voters increasingly placing themselves further to the left while voters for the Nationals have moved further to the right. Liberal party voters have more or less stayed the same while the average voter has moved to the left.



Photograph: Guardian

And here’s the same information, adjusted to show the distance of each voter type from the average voter:

Photograph: Guardian

Informal voters have become more left wing in recent elections but not greatly so, with a high standard deviation suggesting a large ideological spectrum of disillusioned informal voters.



Another way to look at polarisation is to look at perceptions of political parties. Here’s how voters for each of the major parties perceive the Liberal party:

Photograph: Guardian

Labor voters think the Liberals are centre-right and this remains generally stable. However, in 2004 and 2007 they viewed the party as being more rightwing. One explanation for this would be that in 2004 the emotive post-material politics of the Pacific Solution and the Iraq war had taken its toll on core Labor voters but by 2007 the distributional politics of Work Choices antagonised swing voters where they deviated to Labor.

The same is true of Liberal voters, whose opinion of how right wing the party was spiked in 2004 and 2007.

Photograph: Guardian

Since 1996 Australians think of Labor as being more left wing. In 1996 Australians placed Labor at 4.31 and in 2013 they placed Labor at 4.06.

Since 2001, Liberal voters have placed Labor as being more left wing every election. A similar trend is true of Nationals voters, though they place Labor even further to the left. This reflects that Nationals voters are exposed to fewer Labor voters than Liberal voters are and are exposed to neighbourhood effects.

Labor voters have generally considered Labor to be centrist with a small move to the left from 2001 to 2013.

Photograph: Guardian

As for the Greens, Australian voters think they have become more left wing, moving from 3.83 in 1996 to 2.90 in 2013.

Coalition voters consider the Greens to be more left wing than the mean, particularly National voters, who consistently place the Greens lower on the scale than any other voter group.

Photograph: Guardian

We can also see the gap between where voters place themselves, and where they place the party they’re voting for. Labor voters place Labor to the right of themselves, Liberal voters place themselves to the left of where they place the Liberal party, and Greens voters tend to think of the Greens as being more left wing than themselves.



The distance between how the two major parties perceive each other gives us another measure of polarisation.

Photograph: Graph

From this it looks as though the leap in polarisation between the major political parties occurred between the 2001 and 2004 elections. As the standard deviation of the average voter has continued to increase from 2004, it suggests that from that time minor party voters are responsible for the additional political polarisation in Australian democracy.

While polarisation is increasing in Australia, it’s nothing like the levels in the United States. Since 1996 the standard deviation has only increased by 0.4 in Australia. Compare this to the same scale in the American National Election Study where the standard deviation has grown by 2.7.

Methods

The data used here is from the 1996, 1998, 2001, 2004, 2007, 2010 and 2013 Australian Election Study (AES). The data is available from the Australia Data Archive. The AES is a national, post-election, self-completion cross-sectional study which has been run at every federal election since 1987. The data was weighted by sex, age, state and party vote with AEC enrolment data for each election.