The Australian political universe, in the wake of the Labor-Greens preference bro-ha-ha, has focused on the upcoming by-election for the state seat of Melbourne to be held on Saturday. The outcome of this inner city by-election will be closely watched for any impact of the said political conflict between the Labor and the Greens.
Like its Federal namesake the state seat of Melbourne, the distribution of the preferences of Liberal primary votes was crucial to the outcome. In 2010 the Liberals recommended to voters in all electorates to preference Labor above the Green in the lower house ballot and this resulted in approximately 70% of Liberal preferences flowing towards the ALP. The 2010 election result in Melbourne was a TCP Count of ALP 56.17%, Green 43.83%.
However, at the by-election there will be no Liberal candidate, leaving the 28% of primary voters that voted Liberal at the state election without their previous voting choice. The absence of a Liberal candidate will move the final TCP count on its own as the vote will flow to other candidates with differing preference recommendations and may also impact the primary vote of the Labor and Greens’ candidates.
We set out below a “form guide” to all the candidates, their preference recommendation and political affiliations where their party is not indicated on the ballot. We also include the first preference vote shares for the relevant parties at the last state election for both the lower and upper houses. As always click on the image to enlarge.
As always, here at Poliquant, we try to quantify defined political effects and the aim of this post is to determine how the absence of a Liberal candidate at next Saturday’s by-election will affect the result. The result of this exercise will be to create a “par score” which can be used to compare against the eventual result.
There are two steps to this exercise:
- Reassign the Liberal primary vote to other candidates
- Distribute the reassigned vote between Labor and Greens as the likely TCP combination
We look at each step in turn
Where do Liberal voters go?
We have accumulated and averaged the swings of all parties in all state by-elections where no Liberal or Coalition candidate has stood since 2004. We have used the 2004 cut-off as this is when the Greens definitively displaced the Australian Democrats as the largest minor party in Australian politics.
This group of seats all share the same characteristics:
- The seat was previously held by a Labor MP.
- A Labor candidate stood at the by-election
- The seat is metropolitan
Simply put, these seats are generally analogous to the by-election contest in Melbourne on Saturday.
We set out the average swings in these seats in a graph below.
As you can see the bulk of the fall of the Liberal vote is taken up by independents. We have grouped the swings to Family First, Christian Democrats (now Australian Christians), One Nation, Liberal Democrats and DLP as right-wing minor parties, which also gain a portion of the Liberal vote. The Greens also take a slice of the pie.
However, the ALP vote also falls, which slightly “contaminates” the aggregate pool of Liberal voters we are trying to generate. To counteract this we shall assume that any fall in the Labor vote flows to the Greens and the small Labor fall is deducted off the Green rise in the above graph.
Therefore we have a breakdown of the 26.6% average Liberal vote, into the following components: Independents 14.3%, Green 5.8%, RW Minors 6.1%, Others 0.5%.
Converted into percentages we get the following breakdown: Independents 53.6%, Green 21.8%, RW Minors 22.8%, Others 1.8%. Applying this breakdown to the 2010 Melbourne primary vote shares we get the following estimated primary vote shares in the absence of a Liberal candidate.
How will preferences flow?
Thanks to the VEC we can view the registered HTV cards of all candidates here. After perusing the HTV of each candidate we can determine whether they preference Green ahead of Labor or vice versa.
We then assess a preference flow from the groups of candidates in the above graph. For the current by-election, the Australian Christians, DLP and Family First are grouped as Right Wing Minor Parties, the Sex Party is considered the only “other” party and the candidates with no party affiliation on the ballot paper are grouped as independents.
We then assume a preference flow of 70-30 in favour of the party being preferenced by the candidate. As we group the all minor candidates except the Sex Party between independents, Right Wing Minor Parties we take an equally weighted average of all the candidates in each group to arrive at an average preference flow of the group. For the Right Wing Minor Parties group the preference flow is 70-30 ALP as all parties in that group are preference Labor ahead of the Greens.
Amongst the independent candidates we have weighted the preference flow based on the average of all 10 candidates in this group (6 Greens, 2 Labor, 2 open ticket), which equates to a preference flow of 56% to the Greens. However this is where the exercise requires a margin of error as the votes for the independent candidates will not spread equally.
If one independent candidate wins the lion’s share of the votes in this group of candidates then the preference flow will skew towards their recommendation. With this in mind the independent group preference flow to Labor from independents as a group may range between 33.3% and 62%. These are the preference flows that would occur if a single Green preferencing independent candidate (e.g. shareholder activist Stephen Mayne) won 75% of the independent votes or if a single Labor preferencing independent candidate (e.g. Independent Conservative David Nolte) won the same won 75% of the independent votes.
Using the above calculations and assumptions, the effect of the absence of a Liberal candidate at the current by-election is to the turn election into a line-ball contest. Set out below are a full table of the par score calculation and a supplementary table exhibiting the par score band once the full range of independent preferences is taken into account. The central par score is for a thin Green victory at 50.5% TCP. However the range of independent preferences can tip the race either way.
It is important to keep in mind this par score is not a prediction as it does not take into account any change in Labor or Greens primary votes due to other events. But the par score should be considered a baseline from which to judge the reasons for the final result.
A final result that falls within the par score band should be put down to the absence of a Liberal candidate and the structural effect on the vote that brings. If the final result falls outside the par score band then other factors are at play in the result.
UPDATE: Upon inspection of the VEC website today, the HTV of Patrick O’Connor the SEP candidate has changed to an open ticket. Mr O’Connor is grouped with the independents in this analysis as the SEP name is not indicated on the ballot. The post has been amended accordingly.