Are online polls reliable enough?

2011 is election year in New Zealand and this week, Prime Minister John Key and Labour Leader Phil Goff set out their stalls along with Obama-style "state of the nation" speeches.

2011 is election year in New Zealand and this week, Prime Minister John Key and Labour Leader Phil Goff set out their stalls along with Obama-style "state of the nation" speeches.

The pollies will be eyeing upcoming opinion polls, but can the polls be trusted anyway, especially the ones that use online polling?

Despite some success overseas, I doubt such polls are mature enough to be trusted here yet, at least for political polling, even if they do have acclaimed merits of speed and cost.

The Fairfax-owned Sunday Star-Times has begun using Horizon Research, a company that uses online panels.

But its findings have been so far out of line with the others that the polls' credibility is often questioned.

The polls in New Zealand, including those conducted by Australia's Roy Morgan, have tended to show National and its coalition government way out in front, but Horizon keeps showing it in danger of losing its majority.

This has led fellow pollster, David Farrar of Kiwiblog to write a post talking about how trustworthy or untrustworthy polls can be.

Admittedly, Farrar's own market research company, Curia, often conducts polls for the ruling National Party, so he might be biased. But his comments seem fair, especially noting the longstanding records of rival pollsters and these rivals all producing similar results.

So while online polling, especially if you rely on volunteers, is cheaper, perhaps you only get what you pay for. The phone polling or face-to-face interviewing does seem more accurate, especially with random sampling and other weighting. Horizon says it samples and weighs its panels but one could question if it is doing it properly.

Yet pollsters in Australia have been assessing their methodology, with even Roy Morgan testing online methods, though it prefers interviewing people face to face.

Galaxy, which also operates in Australia, seems happy with its online methods, though in Australia, it uses telephones and random sampling for its federal voting intention surveys.

YouGov is another online pollster and is used and trusted by major UK papers, as well as the Economist.

YouGov claims a good accuracy record, citing large sample sizes in its polling — numbers far higher than New Zealand's own Horizon Research.

Maybe this is one of the many things Horizon needs to look at.

Of course in the end, there is only one poll that counts: Election Day. Only then will we truly know who is right!