Newspoll: Is this just a freak result?

Today’s Newspoll via The Oz comes in with the primaries tied at 41 a piece with the ALP down 7 and the Coalition up 7. This washes out into a two party preferred of 52/48 – a 7 point change from last Newspoll. The Greens are steady on 10 while the broad “Others” are unchanged on 8. This comes from a sample of 1149, giving us an MoE that maxes out around the 2.9% mark.

Is this an outlier?

Probably, and it comes from something Newspoll head honcho Martin O’Shannessy said to the Australian.

The majority of the change in the Labor primary vote is attributable to a fall in Labor’s primary among those aged over 50 under 50

The only issue over the last fortnight in media has been asylum seekers, and all the polling we’ve ever had on that issue suggests that it is the over 50’s that are the strongest supporters of tough border protection – and as yesterday’s Essential Report suggested, the over 50’s are also more likely to believe that the Coalition would do a better job at managing this issue..

If this wasn’t an outlier – we would expect the over 50’s to move strongest, so the composition of the poll is inconsistent with what we would expect to occur if the poll was, in fact, an accurate representation of the true state of public opinion.

There is also other evidence for it being an outlier. Firstly, we expect that, on average, 1 in 20 polls are out by an amount larger than the margin of error – which in Newspoll’s case is 3%. Further, we expect that, on average, 1 in 100 of all Newspoll’s will be about by a margin larger than 4%.

This is simply the probability statistics of random sampling in action.

Secondly, this issue has been in the field as a dominant news item for well over a month now. If people were changing their vote so dramatically over the asylum seeker issue, we would have expected to see the ALP vote start leeching away with the last Newspoll, the last 2 Essential Reports and the last Morgan – if not earlier.

Yet that didn’t occur.

Thirdly, all political polls in Australia over any given period of time “move together”. The various pollsters might all have their relative leans – some have a relatively higher vote estimate for Labor, some relatively lower – but they are generally consistent relative leans. Essential Report was in the field over the same period and didn’t pick up any movement at all.

Fourthly, as William Bowe at Pollbludger has pointed out, big moves in the primary vote like this are extremely rare – usually the preserve of polls taken directly after an election, or directly after a leadership change. There are a few exceptions like horror budgets and the occasional, inexplicable random poll (what we would expect), but they are rare.

Finally, this is just completely out of whack:

Only time will tell if public opinion has shifted, and by how much – but on the balance of probability, this is a dreaded outlier.

So kick back, grab some popcorn and enjoy the political show – it should be a doozy. The usual charts come in like this.