Firstly, I used actual votes and actual preference tickets of parties at the 7 September election to predict "point estimates" of likely Senate outcomes under a hypothetical double dissolution. Secondly, I then undertake Monte Carlo analysis by applying a small degree of variation to each party's vote in each state to test the sensitivity of outcomes to slightly modified votes of minor parties. This attempts to simulate the sensitivity of "point estimates" to potential, and as yet unknown, Below The Line (BTL) votes.
In almost all instances, a "half Senate" election is held concurrently with a House of Representative election. This involves the election of six senators in each state and two in each of the two territories, for a total of 76 Senators. But in instances where the Senate repeatedly blocks legislation, the Government may petition the Governor General to call a double dissolution. The most recent double dissolution was in 1987.
Under a double dissolution, each state elects 12 Senators. This means that the "quota" is 7.69%, instead of the 14.29% of a standard half-senate election. It is clearly easier for minor parties to conjure up 7.69% of the vote, including preferences, than it is to reach 14.29%. However, it is also easier for a popular government to achieve a majority in the Senate - to get 4 out of 6 Senators in a state takes 57.1%, whereas to get 7/12 Senators in a state requires a more achievable 53.8% of the vote.
Regular readers, including those following me on twitter, would be aware of how I have used financial modelling techniques (my day job!) to forecast potential outcomes in Senate elections. Tonight, I reveal the application of my model to forecast the likely makeup of the Senate, applying the assumption that all parties votes and group tickets would remain the same as the recent election. While not perfect, it is the best possible assumption we could make.
The "point estimates" of likely Senate outcomes under a double dissolution are as follows:
Double Dissolution likely Senate outcomes, based on 7/9/2013 election results:
Regular readers will recall my statement that the final WA Senate spots are "too close to call". Presently, I credit the Green's Scott Ludlam and Sport's Wayne Dropulich with a 37 vote lead over ALP/PUP. But for interests of consistency, the "current" line above represents an ALP/PUP election. Note that the current vote difference represents a margin of just 0.003%.
In all bar one case, the senators elected in the 7 September half Senate election would also be elected in a full Senate election. But such is the absurdity of the current system that AMEP's Ricky Muir would not actually be elected in a full Senate election where twice as many candidates are declared elected. And in SA, the "No Carbon Tax Climate Sceptics" Party would win the new record for the party elected to the Senate with the lowest vote - 0.11% (approx 1100 out of South Australia's 1,000,000 voters!)
It is striking to note that all three major parties will go backwards under a Double Dissolution, with the "winners" to be a whole host of minor parties with their own single issues and agendas. No less than 12 parties would get a comfy seat on the Red couches at Parliament House.
Monte Carlo Analysis
In order to test the sensitivity of these outcomes, I additionally applied Monte Carlo Analysis techniques to determine likely different outcomes if parties' votes were to change minutely. In this scenario, I have applied a small +/-1.5% variation to each party's vote. This is large enough to produce different percentage likelihoods of election where the election is close, but small enough to output "100% likely" outcomes where the election is not close. This variation is not large - a party with 40% of the vote would vary in the range of (39.4%, 40.6%) and a party with a vote of 2% would vary in the range of (1.97%, 2.03%). The purpose of testing variation in votes is to consider alternative election scenarios in which a minuscule variation in vote may lead to a significantly different election outcome.
SA, TAS and the territories produce 100% likely results. But four states produce outcomes that may vary with just a very small change in primary vote:
NSW: Shooters & Fishers, and the Sex Party both have a 20% likelihood of election
VIC: AMEP has an 18% likelihood of election
QLD: HEMP has a 19% chance of election
WA: The state with highest uncertainty - the Nationals have a 37% chance of election whereas Sport Party has a 7% chance of election.
The AEC has now counted almost all the votes in the Senate - but not all. It has not released BTL preferences for most states either. Accordingly, these outcomes will be subject to minor variation as:
- final votes are counted; and
- final Below the Line vote data outputs are released by the AEC.
If we thought the current Senate was "unrepresentative swill", well we ain't seen nothing yet! A double dissolution held before significant Senate reform is enacted will result in a kaleidoscope of single issue and opportunistic senators and micro-parties.