Retorts

Secondary Heisenberg Effect on Polls

Malcolm Wright [Pulling Polls Apart, Feb] discussed the reasons for the failure of market research organisations to predict the results of recent elections in New Zealand and Britain. An additional factor might be the secondary Heisenberg effect.

Chemists and physicists are familiar with Heisenberg's Uncertainty Principle, which -- in its most general formulation -- states that the physical act of measuring any property affects the property itself, and thus restricts the accuracy of the measurement.

In market research and opinion polling, the primary Heisenberg effect -- which alters the attitudes of respondents to the issues being polled -- is negligible compared with the secondary effect which comes into play when the results of a poll are broadcast.

Apart from affecting the morale of part activists and candidates, poll results can influence tactical voting behaviour and differential turnout. In the recent General Election, there can be little doubt that the strong showing of the Alliance in the last polls impressed many people who were sympathetic to the Alliance, but who didn't want to waste their votes on "no-hopers".

In some countries, the publication of opinion polls is banned during an election campaign on account of the secondary Heisenberg effect. Market researchers can take comfort from the fact that their surveys of consumer preferences for toothpaste flavours and the like are usually not made public, and are therefore not subject to secondary Heisenberg effects.

Derek W. Smith, Associate Professor of Chemistry, University of Waikato