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Is government health policy based on evidence or assumption?

'Food deserts' - evidence and assumption in health policy making BMJ Volume 325, pp 436-8


The overinterpretation of a few small scale studies, carried out up to 10 years ago, could end up being used to determine health policy because the findings fit in with the government's broader policy objectives, argue researchers in this week's BMJ.

Steven Cummins and Sally Macintyre examine the phenomena of "factoids" - assumptions or speculations reported and repeated so often that they are considered true. Using the widely claimed existence of "food deserts"- poor urban areas in the United Kingdom where residents cannot buy affordable, healthy food - they raise important questions about how evidence in public health is produced, interpreted, and reproduced when making health policy.

Three main studies have been used as evidence that food deserts exist in the UK, yet the authors suggest that this research may have been overinterpreted to suit the needs of individuals or groups, and subsequently cited in journals, at seminars, and in the media without close reference to the original source material.

If these three studies had concerned an issue not so eagerly espoused by many in central and local government and public health, and by the public too, and if the issue had been more contentious, the authors suspect that the studies would have been more critically appraised.

The key problem is that the burden of proof, or demand for evidence, may vary according to a policy's perceived fit with current collective world views, they add.

As such, policy makers need to move away from an unquestioning acceptance of conventional wisdom and "expert" advice and cast a more critical and objective eye over the facts, they conclude.


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