Bogus polls compared
The Crafar farms decision has inspired multiple bogus polls asking whether it was the right decision, which gives us an opportunity for comparisons.
Current or recent polls include:
- NZ Herald: 34% in favour of the decision
- Stuff: 22% in favour
- Campbell Live: 3% in favour
(I would link, but these polls tend to disappear quickly from web pages. The pre-decision polls already seem to be gone. )
The Stuff and NZ Herald polls both claim about 18000 votes. If this were a real poll, the maximum margin of error would be under 1%. Clearly the actual error is at least 19%, and quite possibly more.
If the true proportion was about 20% (as in the real poll taken late last year) and you had a real poll with a sample size of just ten you would have a 3 in 4 chance of getting within 10% of the true answer. The chance of having a 30% spread over three polls of size ten would be only 1 in 5. So, on this issue, the self-selected polls are worse than a random sample of just ten people. You can see why we like the term ‘bogus’.
Bogus polls are worse than useless because of anchoring bias. Seeing the results is likely to make your beliefs less accurate, even if you know the information content is effectively zero.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »
Hi Thomas, i think it is because NZ herald has more chinese readers than others. As a chinese, i check nz herald everyday. I personally think chinese will tick yes. Hence, there are more proportion of people chose yes in NZH.
BTW, i am interested if the editors changed the title to ‘Foreign company’ rather than ‘Chinese company’, what the results would be.
13 years ago
The real poll late last year looked at this. There is still majority opposition no matter where the investors come from, but the majority is much smaller for Australia and slightly smaller for other countries.
Most emphatically opposed is Chinese investment, 81 percent opposing such sales, dipping to around three-quarters of those polled opposing sales to Singaporean, Japanese, German and American investors, while 67 percent opposed sales to British investors, and 54 percent opposed sales to Australians.
13 years ago