What to make of the latest opinion polls? Because they diverge so far from each other, experts say one must be wrong.
Perhaps some of those pollsters who got the mood of the Australian electorate so badly out of kilter with the actual election result have been imported to carry out one or other of the two samples. Or, maybe, because the polling done by each organisation covered different periods, there was a dramatic revision in the political mood almost overnight.
Even given the divergence, the pundits were virtually unanimous: Simon Bridges is gone—if not by lunchtime, then some time soon.
That’s, of course, what they said at the time of the last set of polls.
National’s leadership preoccupies these commentators much more than the actual performance of the government.
Over at Kiwiblog, David Farrar – who knows more about the science of polling than any of the political commentators – says the results in the latest two are so far apart that statistically it can’t be a margin of error.
“Let’s look at the four main parties: Labour 42% in OneNewsColmar Brunton and 50.8%% in NewsHubReid Research; National 44% in ONCB and 37.4% in NRR; Greens 6% in ONCB and 6.2% in NRR; NZ First 5% in ONCB and 2.8% in NRR. You basically can’t reconcile these polls. One (or both) of them seem to be outside the 95% confidence interval, ie is the 1 in 20 “rogue” result. The only other plausible explanation is that as the ONCB poll started a few days after NRR, Labour had a massive drop in support after those first few days. But the difference in dates is unlikely to explain the massive gap”.
Farrar further notes the polls even show the direction of change differently. One has Labour down 6% and the other up 3.3%. National is up 4% in one and down 4% in another.
The NZ First result is also outside the margin of error. A 5% and a 2.8% result is outside the 95% confidence interval. Bottom line is that at least one of those polls is wrong. They can’t both be right”.
Perhaps the most egregious bit of reporting from the polling was the headline used by NewsHub over a question on National’s move to leak elements of the budget. According to NewsHub, “Most NZers think National was wrong to leak Treasury budget details”, as if it had sampled the bulk of the population instead of a randomly selected group of fewer than 1000..
The pollsters might start losing credibility as fast as those in Australia did if this is how the results of their work is presented.