When preparing for an election coverage, my first step is always to compile a set of last election results as history for the ABC’s election website and election computer.
The data includes historic votes by candidate and party for each electorate. To enable more complex analysis on election night, the same historic data is collected for each polling place.
When there has been a redistribution, I also re-calculate last election results to match the new electoral boundaries. Those calculations become the stored history for use in analysis.
Another important job is to give all electorates an initial party classification. On election night, party classification is combined with results to label seats as either “gains/losses” or “retains”.
Normally I classify seats based on last election votes. But sometimes I depart from this practice when by-elections, candidate defections and redistributions complicate analysis. Relying too strictly on past votes can make it hard to explain a result on election night.
A prize example is Novembers Victorian election. A major redistribution since the 2018 election has left a number of seats as unclear on how best to allocate an initial party classification.
Recently the Victorian Electoral Commission (VEC) released estimated margins for all seats. You can find the estimates on the VEC’s research and publications page at the link named “Methodology of estimating 2018 election results on new electoral boundaries”.
The table below shows the seats won by party at the 2018 Victorian election on the first line. The second line shows the seat holdings if you strictly apply the VEC’s estimated margins. The third line is the seat holdings I have advised the ABC to use for the Victorian election site (coming soon!) and in the ABC’s election computer.
Victorian Party Seat Holdings – Redistribution Estimates
|2018 Election result
|VEC party seat totals
|ABC party seat totals
A two-page pdf with a new electoral pendulum and alphabetic list of seat margins can be found via this link.
The VEC totals explain why the Labor Party has been reported as having gained two seats through the redistribution. In my view that is not the case. Labor does have two more safe seats than it did on the old boundaries, but at the expense of some marginal Labor seats. The two possible extra Labor seats come about through VEC estimated margins that flip two Liberal seats on fewer than 70 votes.
Whether these two seats are classed as Labor or Liberal held, it has no impact on the swing of around 9.6% needed for the Labor Party to lose its majority
The ABC will be using the same margins as the VEC in most seats. The VEC’s estimates have only minor variations from the estimated margins I published last year. (My original estimates can be found in this post).
The ABC and VEC party totals differ because the ABC is choosing to classify ultra-marginal Caulfield and Hastings as Liberal held (the VEC suggests Labor held) and to keep Mildura as Independent held (the VEC suggests National held). How these seats are classified has no impact on the swing needed for Labor to lose its majority.
There are also four seats where the ABC and VEC agree that party status has changed because of the redistribution.Read More »Seat Numbers and Margins for the 2022 Victorian Election