How the pollsters did in 2017

Now we have a final result we can look at how the public pollsters did. UMR are not included as their full results have not been published but Jacinda Ardern said the day before the election that “Labour is within one point of National in its internal polling”.

I am only looking at how the pollsters did with the four parties that got over 5% as they are the results that matter.

Reid Research were the closest. Their average discrepancy was just 0.7%.

Next closest was Colmar Brunton with an average of 1.4%. Their NZ First result was significantly out.

The next three were all around the same – Roy Morgan, Bauer and Horizon with an average of 2.7% to 2.9% out. Roy Morgan had National 4.4% too low. Horizon 5.95 too low and Bauer 6.6% too low.

Finally the Newsroom/SSI poll which was just an embarrassment. They had National 14.4% too low.

Another calculation I have done is how did the polls do in predicting the gap between the major CR and CL parties or the gap between National and Labour/Greens combined. This is important as it shows who is best positioned to form Government or be the stronger position.

National ended up 1.2% ahead of Labour and Greens combined. Colmar Brunton were very close with a 1.0% gap and Reid Research a 1.4% gap.

Horizon had Labour/Greens ahead by 7.4% so out by 8.6%.  Roy Morgan had L/G ahead by 8.5%, Bauer by 10% and Newsroom/SSI by 21%.

So again the two TV polls were very useful in informing the public as to likely outcomes. The other three were not that useful and one is best not referred to again.