102 seat landslide for Labor

Having run the new quarterly Newspoll figures through the simulation on the old boundaries, it might be time to run them with the new post-redistribution boundaries (thanks Antony Green for the data!) to see the most likely result were an election held in the last three months on our new boundaries for 2010.

The results – the most likely outcome is the ALP winning 102 seats in Parliament, a 19 seat gain on their current position. The charts come in like this and can be read the same as last time.

The reason why there isn’t a great difference in the results between the simulation on the old boundaries and these new ones comes back to the size of the swings being seen, combined with just where on the pendulum the seats were that had their margins changed. Basically, the swings at the moment are large enough that a very similar number of seats would have fallen under both sets of boundaries.  We dont really see the 5 to 6 seat headstart that the ALP received from the redistributions come into play until we get much smaller swings.  With a national two party preferred of 55/45  (and the State swings that combine to produce that national swing) it doesnt actually make much difference, but 53/47 on the other hand, a much smaller swing, produces far more seats for the ALP under the new boundaries compared to the old.

Depending on how the state swings would pan out that made up a national two party preferred of 53/47, we’d expect to see that small 0.3% swing to Labor to deliver somewhere between 4 and 9 seats thereabouts. We can see the “curve” of the seats gained for a given swing under the new pendulum with a simple chart (or course!)

The vertical axis is a given ALP swing – positve is the swing to the ALP while negative is the swing away from the ALP. The bottom axis shows the nth numbered seat in a new Parliament that the ALP would get from a given swing. As you can see, the curve has effectively shifted to the right for the ALP, delivering more seats for a given result, yet it really plays out with swings 1.5% towards the ALP or less.

So the new boundaries certainly benefit the ALP, but the ALP benefit is relatively stronger with small swings than large ones. The larger the swing, the less benefit they get relative to what they would have achieved under the old boundaries.

UPDATE:

Thought it would be worth adding a couple of extra charts. The one above, but with the same curve done with the old boundaires, plus a zoomed out version with both as well to highlight how the big change in the curve occurs at the low swing values.