Analysis Overview

The graphs below serve as an estimate of the possible outcomes for the Western Australia senate by-election. I have used the same primary votes as in the election last year as well as small primary votes for the new parties (based on estimates from other states those parties ran in). The major swings applied are:

LP -5 | NP + 1 | ALP +3 | GRN +1

The motivation for these swings is a best guess on WA polling for the LNP, as well as fantastic ballot position for The Nationals, pulling a small LP vote.

The first graph below is a count of the current primary votes. The second graph estimates the probable number of seats a given party will win. The third graph is the most likely outcome and the fourth graph gives (horizontally) the probability of a particular Half-Senate breakdown (vertically).

Although the above graphs give a good indicator of who can get elected, it helps to see how those candidates are helped or hindered by other parties gaining or losing votes. The analysis will be focused on the effect of changes in major party, and minor party votes, on the chances of HEMP, the Palmer United Party and the Greens of each getting a senator elected.

The two graphs below show the respective chances of HEMP getting elected (vertical axis) against the percentage primary vote they receive (horizontal axis first graph), and the percentage primary vote that the minor parties (not-LP/NP/GRN/ALP/PUP) receive. HEMP's chances rapidly rise after about 0.6%. HEMP polled 1.07% in the last election, which in this election would give them a 29% chance of being elected. However, analysing their ballot position across the country against their primary vote indicates that this large vote is due to ballot position rather than a true party following.

Given this, I believe that HEMP will poll far closer to 0.6%, giving them around a 3-4% chance of being elected.

The Palmer United Party has a small chance of being elected against either the Greens, or the last Liberal Party spot. PUP needs to increase their vote share of 5% from the last election to around 7.2% to give them a better-than-even chance of getting elected. Recent polling has indicated that this might be very possible, and at the expense of the last Liberal Party seat rather than the Greens.

The Greens, on their polling in the last election of 9.5%, have a slightly better than even chance of getting elected. However, with a predicted 2PP swing against the LNP in WA of around 5-6%, and a projected swing to the Greens of anywhere up to 14% according to polling, the Greens are very likely to get up.