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Reckoning with Risk
Gerd Gigerenzer

This book is highly recommended for anyone who has to use numbers to communicate information or who tries to interpret numeric information to make informed judgements.

The book has as its central theme the confusion caused, intentionally or otherwise when information is presented poorly. It presents a truly startling picture of the resulting innumeracy not just within the general public but also amongst trained professionals.

Though the lessons are generic, a significant portion of the book deals with examples drawn from the world of medicine. These are used to illustrate the very simple root causes by which information is presented in ways that obscure meaning and make reasoned judgement difficult if not impossible. These medical examples are far from obscure and deal with issues that will be of concern to many of us, such as data on HIV AIDS, Breast Cancer Screening, Prostate Cancer and use of the contraceptive pill for example.

The thrust of the book is not that information does not exist to assist judgement of risks in these areas, but that the way it is presented and communicated serves to perpetuate innumeracy amongst patient and clinician alike. This innumeracy can have dramatic consequences with inappropriate treatments being selected and patients being caused undue worry, distress or physical harm. An example is cited of a surgeon who performed breast removal operations on 90 patients who showed no sign of disease, simply based on his interpretation of the risk they faced of contracting it in the future.

The examples are not limited solely to medicine and the legal profession comes in for its share of scrutiny including DNA fingerprinting and an insightful look at how innumeracy may have contributed to the outcome of the O.J. Simpson case. The lessons for the broader business community are clear.

The book is divided in to three sections that don’t just provide examples of the problem of effectively communicating data but clear simple guidance on how it can be avoided.

By dealing with topic areas that many of us will recognise the book is able to clearly illuminate the problems of innumeracy and graphically illustrate the impact this can have with lessons for our personal and business lives. It may also provide particularly valuable insights for those who face the specific health problems it uses as examples and help create understanding of the real risks faced for example by a positive breast cancer screening result.

The book also has some absurd but real examples of innumeracy lunacy, for example the Mexican government which increased road volume by simply repainting a four lane highway with six lanes - a 50% increase. The high volume of accidents this caused led to the road being reduced back to 4 lanes - a 33% reduction and the later claim that road volume had actually been increased by 17%! It also has a section of fun examples of innumeracy to help drive the point home and a chapter on teaching clear thinking.

I highly recommend this book as an entertaining an illuminating read. It may help allay unnecessary fears for those facing personal medical problems and will certainly improve everyone’s ability to ask the right questions to get to the bottom of what data is really telling us.

Steve Unwin February 24 2004

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