September 2022

Seat Numbers and Margins for the 2022 Victorian Election

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 55 21 6 3 3
VEC party seat totals 58 19 7 3 1
ABC party seat totals 56 21 6 3 2

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

North West Central By-election

I’ve published a profile on the ABC elections site for Saturday’s North West Central by-election in Western Australia. Results for the by-election are also at the site.

North West Central is the state’s largest electorate taking in 32.3% of the state. It covers 820,591 square kilometres, an area larger than New South Wales. While the state’s largest electorate in area, by enrolled voters North West Central is the state’s smallest. Just 11,189 electors are enrolled to vote at the by-election, just over a third of the state’s current electoral quota of around 30,000.

The by-election has been caused by the resignation of Vince Catania, the Labor turned National MP for the seat since 2008. In what was once a marginal seat, Catania’s two-party preferred vote in 2013, 2017 and 2021 was well in excess of the Liberal/National state-wide vote. Catania appears to have attracted a personal vote amongst Labor voters, shown in the chart below by the big gap in North West Central support for Labor and National between the upper and lower houses at the 2021 election.Read More »North West Central By-election