Accordingly, in a half senate election, the quota becomes 14.29% of the total number of formal votes cast. Under a hypothetical scenario where the Liberal party were to poll 43%, Labor 29% and the Greens 15%, for example, the electees would be 3xLiberal, 2xLabor and 1xGreens, and no further counting would be necessary. Okay, so this is not going to happen! But it is possible that the two major parties may poll in the vicinity of these numbers, reducing the analysis to the final electee only.
I have used the following method for estimating the primary votes of each of the parties:
Step 1: Start with WA 2013 election results
I think these are the recount numbers which potentially understate the Liberal vote by ~1000 votes, or almost 0.1%. But I'm going to disconsider this for the time being.
Step 2: Apply National House of Reps swings to the WA Vote
For this step I take the party swings of the "Bludgertrack", sourced from the sidebar of the Pollbludger blog:
LIB/NAT: 43.0% (= -2.6%)
ALP: 36.0% (= +2.6%)
GRN: 10.9% (= +2.4%)
PUP: 4.0% (= -1.5%)
Others: 6.1% (= -1.0%)
Step 3: Apply additional WA swing to the National HoR swing
Given the WA swing is not the same as the national swing, we need to adjust the swings to represent WA's unique figures. While I'm not sure exactly the data behind PollBludger's National BludgerTrack, I believe it is the longest running and most reputable national poll tracker and the methodology is sound. In the absence of a better methodology, I apply a positive and negative swing to the Coalition and the ALP. Given the party swings above are commensurate with a national swing of -3.4%, and WA has a -3.7% swing, the following adjustments are necessary:
Step 4: Calculate interim expected polling performance
Step 5: Remove the LibDem effect
It was widely reported that the Liberal Democrats vote was much higher in states where they appeared close to the left hand side of the ballot. In WA, they polled an amazing 3.4% - more than the combined vote of the Shooters & Fishers, Wikileaks, Family First, Katter and the Democrats.
The variation to be applied is:
Step 6: Remove the "Could not find" effect
I anticipate that this election will see parties proactively advertising their party name and group. This should be apparent in both pre-election advertising and How To Vote cards distributed by the major parties on election day. (As I'm not from WA, can anyone confirm whether pre-election advertising is inclusive of the party's group??)
The extent to which I am removing this effect is questionable. But I am modelling that two-thirds of voters who previously voted non-OTH in the House but OTH in the Senate will revert to non-OTH votes in this WA Senate election.
I am anticipating the following variations:
Step 7: Remove the Wirrpunda effect
Conventional wisdom states that where parties run popular footballers, their vote increases. That's why they keep preselecting them! This is especially true in the AFL states, but perhaps less true in the NRL states.
The WA National vote was the highest since 1987, and they also got 30% more vote than they got in the House of Reps (5.1% vs 3.9%)
I am modelling the following variations:
Step 8: Add it up
Doing the sums, I end up with the following estimated votes
Step 9: Assign OTH vote
The biggest swing above is the sharp decline in the OTH vote - but given the fact parties will be able to advertise group numbers and the intense focus on the parlous nature of voting for the flying aliens party (or similar), I think this is reasonable. So I started by unilaterally assigning votes to the first few groups, recognising Donkey or partial Donkey voting patters that will apply to parties like Wikileaks (Group A). I have then estimated vote for the remaining parties using common sense and previous polling performance, and then I returned and ratioed down estimations to ensure the vote is 100%. I assigned party votes in groups, rather than attempting to precisely estimate each party's individual vote. (I have not used this method to increase the Group B Nationals)
After ratioing down the minor party votes, I end up with the following estimated primaries:
0.77%: Wikileaks, Sex
0.58%: Shooters&Fishers, LibDems
0.42%: Family First
0.27%: Animal Justice, Motoring Enthusiasts, Democrats, DLP, Christians, HEMP, Woolf&Verity, Katter, Pirates
0.19%: Freedom&Prosperity, Outdoor Recreation, Rise Up, Smokers, Sport, Sustainable Population, Voluntary Euthanasia
0.10%: Building, Mutual, Republicans, Socialists, Secular, Voice
Sure, these are low. Looking at a lot of these parties, you might think these numbers are low. Please tell me where precisely you think in comments, but please also tell me how my methodology for the low OTH vote is also obtained, or which party's vote should be correspondingly lower.
At this point, I have applied the methodology as previously posted here.
In order to undertake any Monte Carlo Analysis, I need to estimate variance for each party's vote. I have used the following linear vote variations:
ALP & LIB: +/- 15% (That is, ALP vote varies within the range of 30.9% +/- 4.6%)
GRN: +/- 30% (That is GRN vote varies within the range 12.2% +/-3.6%
All others: +/- 50% (so FF would vary in the range of 0.42% +/-0.21% or between 0.21% to 0.63%)
These ranges are quite wide, necessarily. If a party's vote is within its variance and there are no Monte Carlo simulations that elect that party, it is extremely unlikely it will actually be elected!
If you've made it this far, you probably want to know the estimated results.
Firstly, you can check any given "point estimate" of votes by using Antony Green's Senate Calculator. But the importance of the Monte Carlo Analysis is that it enables us to easily identify where outcomes will be different for small/feasible variations in parties' primary votes. For example, run AG's calculator using default votes. Then run it again, but increasing NAT's vote from 5.07 to 5.2%. Spot the difference? In the latter case, the NAT candidate gets elected instead of the PUP candidate. But also note the default values do not incorporate latest polling, whereas the numbers above do.
Very likely senators: (>90% probability)
LIB: 3 (3rd senator with 95% likelihood)
ALP: 2 (2nd senator with 99.7% likelihood)
ALP (3rd): 4%
LIB (4th): 3%
So, what do you think?
UPDATED 2:30pm 21 March
I have also run some additional scenarios, with a higher percentage of votes for minors: 11.9% instead of 7.8%. Surprisingly, not much changes.
1.18%: Wikileaks, Sex
0.88%: Shooters&Fishers, LibDems
0.65%: Family First
0.41%: Animal Justice, Motoring Enthusiasts, Democrats, DLP, Christians, HEMP, Woolf&Verity, Katter, Pirates
0.29%: Freedom&Prosperity, Outdoor Recreation, Rise Up, Smokers, Sport, Sustainable Population, Voluntary Euthanasia
0.15%: Building, Mutual, Republicans, Socialists, Secular, Voice
The results are as follows:
Very likely senators: (>90% probability)
LIB: 3 (3rd senator with 96% likelihood)
ALP: 2 (2nd senator with 98% likelihood)
ALP (3rd): 2.3%
LIB (4th): 0.7%
FREE: 1.3% (Yes, this is the "Freedom and Prosperity Party"
Or, in summary - this change makes precious little difference to the 3-2-1 scenario referred to above - just slightly more scatter at the margin for one of a number of minor parties.