Revealing data

The Greens had a particularly good showing in the 2010 Federal election, winning their first lower house seat in a general election, receiving their highest ever share of the primary vote, and increasing their Senate representation to nine. Concerns have been raised in the Victorian state branch of the ALP, however, that these gains came at the expense of the ALP. So, how seriously should the ALP be concerned about the Greens?

To examine this issue, I created state-specific scatter plots tracking electorate-level results from the last four Federal elections. In each plot, the vertical axis represents the percentage of primary votes cast in favour of the Greens while the horizontal axis represents the ALP two candidate preferred vote.

As the plots indicate, the Greens primary vote has been rising since the 2001 election. These increases have occurred irrespective of whether the ALP two candidate preferred vote has trended towards the ALP (Victoria, South Australia, Tasmania, ACT, NT), away from the ALP (Western Australia), or moved in every-which direction (New South Wales, Queensland). As such, there does not appear to be a consistent relationship between the Greens primary vote and the ALP two candidate preferred vote.

So, should the ALP be worried? Yes and no. In most electorates, the Greens are unlikely to threaten ALP candidates, at least in the foreseeable future. The exceptions are in inner-city electorates held by ALP MPs. In 2010, for instance, the Greens primary vote exceeded that of the Liberal Party in three electorates (Grayndler, Melbourne, and Batman), forcing a run-off between the Greens and the ALP. One of these electorates (Melbourne) ended up going to the Greens, and future gains in the Greens primary vote could also see the seats of Grayndler and Batman come into contention.

Notes:

• An explanation of the two candidate preferred vote can be found at the AEC website.
• Four electorates (Kennedy, Lyne, New England, and O’Connor) were not included in the plots because the ALP was not represented in the Two Candidate Preferred Vote.

Source:

• Australian Electoral Commission