The pendulum orders every seat in the country by the swing required for that seat to change hands. By following the pendulum you can determine roughly how many seats will fall with a particular national vote. Antony Green has built a calculator which can work this out for you.
Following the pendulum only gives you a rough idea of what might happen. Some seats will swing more strongly, and others won’t, thanks to a whole bunch of factors including the incumbent MP, election issues, and demographics.
So how do we identify which seats could see larger-than-average swings and fall despite a seemingly ‘safe’ position on the pendulum?
One factor worth considering is how much the seat has swung since the last Coalition victory in 2004. While many marginal Labor seats swung back to the Coalition in 2010, a number of seats, mainly in Victoria and South Australia, swung even further to Labor in 2010.
There are fifteen seats where the cumulative swing from the Coalition to Labor at the 2007 and 2010 elections is greater than 9%. These are a good place to start when looking for the big swingers.
Read below the fold to find out where those seats are.
|Seat||State||2013 margin||Cumulative swing|
Thirteen of these seats are held by Labor. Forde is the only seat on this list to swing against the ALP in 2010 – it’s on the list due to a massive 14.4% swing away from the Liberal Party in 2007.
The list is complicated by the existence of redistributions, but luckily most of these seats were unaffected by redistributions. Only Bass, Dobell, Forde and Lyons were affected by the redistribution, and in none of those seats was the margin affected by more than 0.5%.
You’ll notice most of these seats, including all of those at the top of the list, are in South Australia and Victoria, which generally swung towards Labor in 2010.
I’ve bolded six seats where the margin at the 2013 election is less than the cumulative swing over the last two elections. While three of these seven seats are considered to be reasonably marginal, and are likely to fall to the Liberal Party, the other four are held by quite large margins.
Makin, Wakefield and McEwen, however, are all held by margins of more than 9% despite a recent history of being considered “marginal”. The Victorian seats of Holt, Ballarat and Isaacs and the Adelaide seat of Kingston don’t quite fit this criteria, but these seats would be very close if Labor’s cumulative swing flows back to the Liberal Party.
There could be a bunch of reasons why these seats look so different on paper to how they looked in 2004: demographic change, particularly popular local members could have such an affect. But it could also suggest that the Labor margin is pumped up with a lot of soft voters who could easily decide to switch back to the Liberal Party.
If you’re looking for seats which could fall despite sitting quite far up the pendulum, it would be smart to start with the Melbourne seats of Holt and Isaacs, the rural Victorian seats of Ballarat and McEwen, and the Adelaide seats of Kingston, Makin and Wakefield.