A Few Charts.
Posted by Possum Comitatus on August 11, 2008
Just thought I’d whack up a few charts of things I’ve been looking at over two-party preferred margins lately.
First up, Newspoll TPP margins for every Newspoll going back to Novemember 1985. Newpsoll had a few periods where they didn’t calculate TPP results in their polling, so I’ve constructed a TPP series using the primary vote estimates and distributing preferences the further away from an election you get, the less the results get distributed according to that previous election and the more they get distributed on the basis of the results of the approaching election (click on these to blow them up).
It’s interesting how election results interrupt the longer running trends – sometimes it’s the dreaded narrowing, sometimes its the opposite.
Next up, if we measure the TPP vote of the winning party for every election back to 1949, as well as the percentage of seats that the winning party achieved from that vote and chart them with a scatter plot and a trend line (quadratic trend) we get:
This gives us an alternative to the pendulum for projecting how many seats a given TPP vote would be expected to deliver to the victorious party. If we transform those percentage of seats won to actual seats in a 150 seat parliament (which we have today) we get:
Which is really just a bit of fun, although the cluster of results where a party won government by getting less than 50% of the vote makes things a bit more complicated here.
Finally, a little chart on the way that One Nation permanently reduced the Coalition primary vote. It’s again using Newspolls but I’ve also added a quadratic time trend through the results with a regression that has a One Nation dummy variable in it (which starts at the first Newspoll after the One Nation Party was created).
I hope you find it as visually interesting as I do in terms of the pronounced impact of One Nation on the Coalition vote.
The US Election Intrade data has suffered its weekly update, showing Obama getting his second week of probability flight in a row.