Via Andrea Vance’s bottom-feeding troll feed:
This attitude towards the Morgan poll seems to be a thing around Parliament rather than just Joyce spinning a bad result. Lots of journalists and staffers have told me that they don’t trust the Morgan poll, that it’s ‘always bouncing around’ etc. And the Morgan poll is always ‘bouncing around’, because the Morgan poll is roughly every two weeks, while Fairfax, say, only poll three or four times a year. Polls are noisy datasets and they jump around a bit but if you poll frequently you can generally see trends in the data while if you have very long gaps between your polls any changes you see might just be random noise.
David Winter and Gavin White both looked at how the polls performed when predicting the actual outcome of the 2011 election. I aggregated Gavin White’s data for the different parties and graphed them to show overall predictive accuracy for each pollster. (A zero would mean your poll result was totally accurate predictor – so the larger the bar the worse you did).
The Morgan poll is about middle of the pack. Their latest one might not be accurate though. It’s only one poll. After all, the gallery and political pundits all warned us that the departure of universally beloved blue-collar bloke Shane Jones meant the utter annihilation of the Labour Party, and this Morgan Poll shows them gaining tens of thousands of center voters, even before the Williamson resignation and Collins melt-down – so maybe it is a rogue. I guess the other outlets are waiting until after the budget to conduct their polls, so we might have to wait a while before we get additional data.
(NB: As Pete points out in the comments there’s an element of luck here. You might have a really accurate poll that happens to get one bad result just before the election and so you’d do poorly on this analysis.)