Auckland stadium polls may be misleading

Public opinion polls on the Auckland stadium issue are unscientific and don’t necessarily represent the views of all Aucklanders, says polling expert Professor Phil Gendall.

The Marketing professor says it’s also likely the polls are being used as a lobbying tool by vested interest on all sides of the debate.

He says the scientific principles of polling are well established. “To measure public opinion, it is not necessary to question everyone; by selecting a representative sample you can, within certain limits, be confident that their views reflect those of the population in general. This can provide an important input into the democratic process. However, the critical point is that the sample must be representative of the population from which it was selected. If it isn’t, then we don’t know how generalisable its opinions are.”

He says that is the problem with most of the polls conducted on the Auckland stadium issue: “They are generally based on self-selected samples of people with the time, the motivation, and sometimes also the money (and access to a computer or a copy of the New Zealand Herald), to participate. “It is impossible to say how representative of Aucklanders in general the opinions of these self-selected samples are, even if the numbers involved are quite large.

“Phone-in or email polls are also susceptible to manipulation or ‘ballot stuffing’ unless they are very carefully conducted. That is another reason why they are likely to reflect the views of people with strong opinions one way or the other. It doesn’t mean the polls are wrong, just that there is no way of telling if they are right.”

Professor Gendall says this doesn’t mean the polls are of no use to the City Councillors who have to make the decision on the waterfront site by Friday. “If they understand their limitations and make due allowance, they may gain some insight into the prevailing public mood from their results.”

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