Dr Bryce Edwards
Patrick Gower hit the nail on the head last night when he was asked to explain the latest Newshub poll results: volatility. It has been one of the strongest themes of this election campaign, with its various twists, turns, leadership changes, and poll results of the last two months. You can watch Gower put his case to Labour’s leader on The Project last night – see: 'Well that was awkward' – Jacinda Ardern grills Patrick Gower over Newshub-Reid poll results.
The word “volatile” is used in many of the reports about last night’s surprising Newshub poll – see Anna Bracewell-Worrall and Patrick Gower’s National could govern alone in latest Newshub poll. In this report, Jacinda Ardern also says there has been “real volatility” in the polls, and hence Labour and the Greens are not panicking over this poor result. But with National on 47 percent, Labour ten points behind on 37, and the Greens below 5 per cent, the poll was certainly seen as a shock result.
The political editor of Stuff, Tracy Watkins, says this latest poll “confirms what we all knew – this election is a roller coaster… This election is truly volatile” – see: National surges ahead in new poll. She emphasises this by asking us to “Think back to just two months ago – the political landscape now is unrecognisable from back then.”
Ms Watkins also brings up the difference in results between the Newshub poll and TVNZ’s recent Colmar Brunton poll: “Traditionally the two big polls – Newshub and 1News – have been accurate to within a few points of previous election results. But on the latest numbers the two polls are eight points apart, even though they were taken over roughly the same period. That could be a pointer to huge volatility in the electorate.”
Is Labour’s tax vulnerability to blame?
Most commentators are explaining National’s rise as a reaction to the debate about Labour’s tax and fiscal policies. Ms Watkins says in a second column on the poll that it’s proof Labour is vulnerable on tax: “The lack of clarity has left holes big enough for National to drive a very big truck through. It has sown the seeds of uncertainty about a raft of other taxes, including an inheritance tax, and Labour's plans for a water tax has stirred up a brewing farmers' revolt. The poll may even be a validation of National's big $11.7 billion fiscal hole gambit” – see: Voters punish uncertainty, and Jacinda Ardern's left enough of it for National's attacks to work.
She proposes that Labour needs to fix this problem: “Ardern needs to be clear about what's on or off the table by releasing the terms of reference, and even the likely makeup of the group. And if she really wants to put the issue to bed, she should make a cast-iron promise not to implement its recommendations till she seeks a fresh mandate.”
Similarly, Vernon Small also wonders if “National's attacks on the uncertainty of Labour's plans for a post-election tax working group are taking their toll” – see: Jacinda-effect checked and reversed as National jumps into big lead.
It is NBR’s Rob Hosking, who seems most certain that Labour’s tax stances have seen their rising support stall: “The cuteness around tax from Labour is the big issue over the past 10 days and it seems probable this is causing a few more sceptical glances from undecided voters. Ms Ardern has broken one of the cardinal rules of politics, which is this: Don’t insult people’s intelligence. She and finance spokesman Grant Robertson have been too cute by three-quarters on their plans in this area, starting by saying they would leave a capital gains tax, or other types of taxes, to a working group of tax experts. ‘I’m not a tax expert,’ Ms Ardern proclaimed at one point, deferring all questions until after the election” – see: Latest poll derails Labour's 'inevitability' narrative (paywalled).
Mr Hosking complains Labour is playing a game over tax, which voters don’t like: “Yet she and Mr Robertson have, day by day, added to the list of tax changes they will not bring in: no changes to company tax, no changes to personal income taxes or GST, no inheritance tax, and any capital gains tax won’t go on the family home. Nor – after a confused few hours when it was plain Ms Ardern was not sure of her ground at all in this area – will a land tax affect the family home. In other words, it is becoming pretty clear Labour knows exactly what it wants to do on tax but isn’t prepared to say so. New Zealanders tend to punish this sort of behaviour on key issues: A government that thinks its citizens are this stupid is not to be trusted.”
Other explanations for the change in the polls
While also pointing to Labour’s tax problems, Herald political editor Audrey Young identifies some others: “Paula Bennett's ripping into gangs may have helped. And National's plan to cut the benefit of young people who refuse take up the offer of work experience may have helped … The other factor is English himself. Boring but dependable, he has had more exposure in the past two weeks than he has had in the past nine months as the guy who had to step into John Key's shoes as prime minister” – see: Bill English gets his wish as Jacinda Ardern 'stardust' appears to settle in new poll.
Likewise, the Spinoff’s Toby Manhire wonders if maybe “the Ardern halo has lost some shine” and whether Bill English had impressed in the leaders' debates: “Has Bill English’s strength in the debates – under considerable pressure, he has stayed strong, phlegmatic – been underestimated amid Jacindamania?” – see: Dramatic? Yes, it bloody is: National surge into big lead in new Paddy-poll.
How reliable are the polls?
The difference between the Newshub poll and the Colmar Brunton poll – taken roughly at the same time – is not about volatility of course but about the accuracy and consistency of polls. On social media there has been a barrage of challenges to this poll, with all sorts of questioning of its methodology, and general doubts about its accuracy.
For an excellent discussion of poll methodology and accuracy, see Katie Kenny and Andy Fyers’ Political polls explained: The how, the why, and the what does it take. They report that “A look at past elections shows that pollsters have, collectively at least, done a pretty good job at prediction of the outcome of the election.”
But there are possible problems with polling, and they outline three issues to watch out for: the margin of error, “non-sampling errors” such as the use of landlines, and voter turnout levels. But, they emphasise the importance of aggregating the various polls, and looking at back at previous elections, “With a couple of exceptions, the Poll of Polls had the support for each party right to within 1 to 1.5 percentage points.”
For more on these issues, you can listen to Professor Malcolm Wright from Massey University talk today to Guyon Espiner on Morning Report – see: Election 17 political polls: How do we interpret them?
It’s worth keeping a watch on all the various “poll of polls,” all of which use different methodologies to combine the available survey data. For example, see the Stuff poll of polls. RNZ also has Colin James’ poll of polls, and for the latest on this, see: Newshub poll puts National out in front.
But some statisticians are coming up with even more sophisticated ways to use the data and make forecast results. The most interesting is the Herald's Election Forecast. This is projecting National to win 54 seats to Labour’s 53.
Or you can go betting on the internet. The Australian Sports Bet website has Labour as the favourite to “to provide the PM after the election.” It’s paying $1.72 for a Labour win, National at $1.91, the Greens at $51, and NZ First at $67 – see: 2017 General Election.
And there are more polls coming. The next due out is the 1News Colmar Brunton survey, which we will see tomorrow night.
Finally, for satire about this tight and volatile race, see my blog post, Cartoons about the rivalry between Jacinda Ardern and Bill English.