Healthy Skepticism Library item: 16180

Warning: This library includes all items relevant to health product marketing that we are aware of regardless of quality. Often we do not agree with all or part of the contents.

Publication type: Journal Article

Black S.
Statistics for health: Let’s communicate risk clearly
BMJ. 2009 Jul 28; 339:
http://www.bmj.com/cgi/content/extract/339/jul28_3/b3034

Abstract:

Heath understates one important issue in her observations on breast screening1: the systemic illiteracy of doctors, epidemiologists, and other health professionals in communicating statistical results.

Gigerenzer pointed out just how badly professionals misinterpret risk when given the data as conditional probabilities.2 He contrasted this with the (much improved) results when the facts are communicated as natural frequencies. Despite this we continue to use the format that doesn’t work.

I have used the statistics around screening for HIV, prostate cancer, and breast cancer to show decision makers why the way you communicate the facts affects people’s ability to make sense of them. Surprisingly, public health people in the NHS are often shocked at the implications of the statistics on breast cancer screening once they understand them (they often seem to start with a belief that mass screening programmes are an effective public health intervention).

We need to stop assuming that . . .