A new poll

Stuff has got back into the polling business, having published a poll done by YouGov.

It’s great to see another public pollster. Before this we only had One New Colmar Brunton and Newshub Reid Research. If Newshub dies, then we may have been left with just one public pollster.

But fair to say the results of this poll are quite different to the two recent TV polls. Here’s how they compare:

• National – 38% (SYG), 47% (ONCB), 43.9% (NRR)
• Labour – 41% (SYG), 40% (ONCB), 41.6% (NRR)
• NZ First – 8% (SYG), 4% (ONCB), 4.0% (NRR)
• Greens – 8% (SYG), 7% (ONCB), 6.3% (NRR)

So the three polls broadly agree with Labour and Greens but disagree on National and NZ First.

The differences for National and NZ First are well beyond the margin of error.

So what this means is that either there has been a massive change since the TV polls (mid Oct to early November) or one or more of the polls are wrong.

YouGov polls are done entirely through online panels. YouGov is a very good company globally and has a good track record in the UK of accuracy. In the US their record is more mixed. Five Thirty Eight gives them a B- rating.

In New Zealand the accuracy of online panel polls with elections hasn’t been great. Let’s look at the 2017 polls:

If you look at the gap between National and Labour-Greens ONCB had it at 1.0% and NRR at 1.4%. The actual was 1.2% so pretty damn good. The online panel Horizon had the gap at -7.4% and Newsroom/SSI at -21%. So massively off.

YouGov has shown in the UK that online panels can be accurate for political polling, but it isn’t easy. You need a very large database. You need to make sure your recruitment isn’t skewed, and you need to make judgement calls on weighting.

As I said it is a good thing YouGov are now polling in New Zealand, but I’d caution against reading too much into their initial poll. As always, it is the trend that matters.