UK and US results make NZ pollsters nervous

British Labour Party leader Jeremy Corbyn defied major political polls by tapping into the youth vote. Photo / AP

After poll-defying results in the US and UK elections, New Zealand pollsters are admitting a few nerves in election year.

"They weigh on my mind, definitely," said National Party's pollster David Farrar, of Curia Market Research.

But he and other pollsters are confident they are not blind to a Donald Trump or Jeremy Corbyn-like shock in New Zealand.

UMR Research executive director Stephen Mills, who polls for the Labour Party, said rising scepticism of political polls was mostly unwarranted.

"There hasn't been any sort of systemic polling failure in a New Zealand or Australian poll in my lifetime. We're not going to be going back to reading rabbit entrails any time soon."

At the 2014 general election, most New Zealand major polls were mostly accurate and predicted parties' party vote within the margin of error.

New Zealand's relatively high voter turnout and MMP system made their job easier.

"A 1 per cent difference in MMP is one seat," Farrar said. "A 1 per cent difference under FPP [in the UK] can be 30 seats, or 50 electoral votes in the US."

In the recent UK election, pollsters wrongly assumed that youth voting would follow historical trends. Instead, it surged from 43 per cent in the 2015 election to an estimated 72 per cent, driven by youngsters feeling disposessed by the Brexit referendum.

In the US, pollsters correctly predicted that Hilary Clinton would win the popular vote, but badly underestimated the turnout of non-college, white voters in the "Rust Belt" states, who strongly favoured Donald Trump.

New Zealand pollsters are keeping a close eye on voter enrolments to make sure there are no unusual trends here, but are not making drastic changes to their methods.

Mills said analysis of social media and early turnout numbers had not improved traditional polling methods.

"It is getting harder with greater and greater volatility," he said. "But [traditional polls] are still the best way of getting as good an idea as you can about what's happening."

The fall in the number of polls and frequency of political polling in New Zealand could increase the possibly of a surprise in September, Farrar conceded.

But three months from election day, there is little of the upheaval or polarised debate witnessed overseas.

Farrar said one of the best indicators was Curia's "Is the country headed in the right direction?" question.

"In the US, it's been negative for 17 years. In the UK, negative for pretty much the last ten. In New Zealand, it's been positive, you're talking 60-40, constantly since 2008.

"Things can change, but it tends to indicate we're a more stable political environment."

General election 2014: How the pollsters fared

• Official result (21 Sept)
National: 47.04
Labour: 25.13
Green: 10.70
NZ First: 8.66
Maori: 1.32
Act: 0.69
United Future: 0.22
Conservative: 3.97
Internet Mana: 1.42

• Herald-DigiPoll (11-17 Sept)
National: 48.2
Labour: 25.9
Green: 11.1
NZ First: 8.4
Maori: 1.1
Act: 0.5
United Future: 0.2
Conservative: 3.3
Internet Mana: 1
Total variation: 4.11

• Stuff-Ipsos (2-17 Sept)
National: 47.7
Labour: 26.1
Green: 12
NZ First: 4.5
Maori: 0.9
Act: 0.69
United Future: 0
Conservative: 4.5
Internet Mana: 0.9
Total variation: 9.17

• One News Colmar-Brunton (13-17 Sept)
National: 45.1
Labour: 25.2
Green: 12.5
NZ First: 8.1
Maori: 1.6
Act: 0.6
United Future: 0
Conservative: 4.4
Internet Mana: 1.8
Total variation: 5.8

• 3News-Reid Research (9-15 Sept)
National: 44.5
Labour: 25.6
Green: 14.4
NZ First: 7.1
Maori: 1.1
Act: 0.1
United Future: 0.1
Conservative: 4.9
Internet Mana: 2
Total variation: 10.71