The graph accompanying my last post for The Guardian appeared as a low-res PNG. Here is the original, click on the in-line version for a standalone version.
I got some Twitter traffic as to why I’m modeling 1st preferences. The short answer is “first things first”. My strategy is (1) do my model-based, dynamic, poll-average of the 1st preferences, then (2) overlay assumptions about preference flows for 2PP estimates. That is, each pollster is allocating preferences to their 1st preference estimates; each pollster has only so much sample underlying their 1st preference estimates, so the 2PP estimates inherit that. My thought is to get a more precise estimate of the 1st preferences from my statistical model, *then* assign preferences. The aim is to wind up with a more precise 2PP estimate at the end of the process.
The easier thing to do is to simply average the pollster’s 2PP estimates (and I may yet wind up doing that). And it could well make very little difference.
An observation: if Green + Other etc is relatively constant (and this seems plausible, at least for short time frames) and the preference flow from those voters to Labor (conversely, the Coalition) is also rather steady (and everyone assumes it is, by the way), then Labor 2PP = Labor 1st preferences plus a term that is approximately constant.
Thus, variation in 2PP is almost all driven by variation in Labor 1st preferences, if what I’ve asserted in the previous paragraph is correct. The implication is that you don’t lose much by looking at 1st prefs vs 2PP, at least over the short term.
One the other hand, if Labor is shedding/gaining votes to/from its Left (the Greens) and not the Coalition, then no, Labor 1st prefs won’t track Labor 2PP particularly well, since the vast bulk of those Green votes flow back to Labor via 2nd preferences. I’ll have more to say on this once I’ve done some more work with the modeling and the data. But it is my intention to produce 2PP numbers one way or the other.
I’m back in the USA now, having spent June in Sydney and Brisbane. Our last night in Australia was in Brisbane with family and friends on Wednesday night, watching politics and State of Origin (and then politics again).
I tweeted out Thursday morning’s Courier Mail cover. We’re going to frame that one.