Risk is integral with life. It ceases only when life ceases. If you manage risk badly, your exit may be sooner than you wish: a good reason for studying the subject carefully. Much of the literature of risk is excellent, and Gerd Gigerenzer ¨C whose work Malcolm Gladwell drew on extensively in his best-selling book Blink: The Power of Thinking Without Thinking ¨C is a leading contributor to this excellence. A very important paragraph is nearly the last in this book; it should have been the first. In it Gigerenzer explains why Risk Savvy is not an academic textbook: he wishes to give something back to the taxpayers who fund his research; he does not wish people to be further estranged from science; he seeks to enable readers to take more control of their lives by making more informed decisions. Would that these principles were compulsory throughout the academy.

Similarly, perhaps the book¡¯s most important chapter, ¡°Revolutionize School¡±, is left to last. Gigerenzer advocates a risk literacy curriculum for schools, starting young. His curriculum has three topics: health literacy, financial literacy and digital risk competence, each subdivided into statistical thinking, rules of thumb and psychology of risk. This is a revolution that we should all actively support; it would equip children to deal with the real world. It would put touchy-feely dream-world teaching into context and, with luck, into oblivion. Michael Gove, are you listening?

Remember the ancient Persians; they never took a decision when drunk that they did not review when sober, and vice versa

Much of Risk Savvy focuses on the natures and forms of incoming risks, and the various corruptions, games and mechanisms adopted by those seeking to benefit from misleading you on the risks that they present. Gigerenzer is right to highlight the fundamental failings of bureaucratic countermeasures. They are complex, costly and ponderous, a waddling reset of the battlefield defences, no great impediment to an agile enemy who evades them with new corruptions. Your most reliable defence is you. Become risk-savvy. Understand risk. Understand the mechanisms of deception. Understand how your own mind may deceive you. Understand how to take evidence-based decisions.

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Unfortunately, in the process you will need to grasp some statistics. Gigerenzer is very good at explaining their misuse, and in doing so examines two major pitfalls. The first relates to probabilities, which he illustrates with a cautionary tale of the 1995 UK Committee on Safety of Medicines. The committee warned that third-generation oral contraceptive pills doubled the risk of thrombosis. The risk associated with the second-generation Pill, 1 in 7,000, was increased to 2 in 7,000 in the new Pill. Distressed women stopped taking the Pill. Unwanted pregnancies and abortions ¨C with all their associated risks ¨C resulted. Although the relative risk of thrombosis did indeed double, the absolute risk, the real risk, increased by only 1 in 7,000. In added irony, the risk of thrombosis is greater with pregnancy or abortion than with the third-generation Pill. First statistics lesson: always ask, what is the increase in absolute risk?

Gigerenzer¡¯s second lesson is that, if figures are expressed not as probabilities but as natural frequencies, their significance is much more obvious. His example is of 1,000 women, 10 of whom have cancer and 990 of whom have not. Mammograms indicate cancer in 9 of the 10 who have it, and in 89 of the 990 who have not. Thus 98 of the 1,000 women test positive. All will be horrified. But how reliable is their test? What is their true probability of cancer? Expressed as a natural frequency the answer is clear, under 10 per cent, 9 (who have cancer) divided by 98 (the 9+89 who test positive). The same calculation using conditional probabilities (technically by using Bayes¡¯ rule) has baffled many doctors over the years, thereby greatly and unnecessarily distressing hundreds, perhaps thousands, of women. Second statistics lesson: reject conditional probabilities and insist on natural frequencies.

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In these examples, the supposed expertise of clinicians most certainly did not extend to statistics. Their unfortunate patients trusted them, unaware of their illiteracy in statistics. In courts of law the same ignorance in ¡°expert¡± witnesses, and in the presiding judges, can lead to dreadful miscarriages of justice. In Gigerenzer¡¯s view, even more culpable is the deliberate misuse of statistics by vested interests, notably the pharmaceutical industry. They do not compare like with like. They cherry-pick their sample groups and/or their statistical methods to ¡°prove¡± the efficacy of their product. Gigerenzer describes this with the musical term ¡°double-tonguing¡±. Whatever you call it, never forget that snake-oil salesmen speak with forked tongue. Your best defence is to become a well-informed manager of your own risks. To do this, you must grasp elementary statistics. Gigerenzer¡¯s clear explanations will be a great help to all. The daunted may prefer his earlier book, Reckoning With Risk: Learning to Live with Uncertainty, which covers statistics at greater length, and thereby with greater clarity, than Risk Savvy.

The subtitle of this book is How To Make Good Decisions. It rightly includes the mind itself as an important source of bad decisions. Your mind is always trying to make itself comfortable. First and foremost it likes quickly to make sense of things. To do this it gets up to all kinds of games, seeking to take rapid decisions that it then defends by means foul and fair, grasping for supporting information while firmly rejecting conflicting information. Risk Savvy explains some of these mechanisms: false certainty, the certainty illusion, and the turkey illusion, ie, because the nice farmer has fed us every day, he always will. Gigerenzer draws valuable lessons: do not be impulsive in data-rich situations where you should be thoughtful; do not be thoughtful in data-poor situations where you should be intuitive. Remember the ancient Persians; they never took a decision when drunk that they did not review when sober, and vice versa. Cheers.

Although Risk Savvy is intended for a general readership, it remains a thoughtful treatment of a wide-ranging and demanding subject. Few readers seeking to absorb its contents will do so at first reading. They will wish to revisit tricky concepts and detailed arguments. Here the publisher should have helped. The book¡¯s notes do not state the pages to which they refer; in following a series of references the reader will soon run out of fingers. The chapter headings are jokey; this is probably not a good idea in a thoughtful book, and is most certainly a bad idea when not accompanied by brief chapter synopses. In contrast, Better Doctors, Better Patients, Better Decisions: Envisioning Health Care 2020, a collection of papers Gigerenzer co-edited with J. A. Muir Gray, is a model of clarity, each paper starting with an abstract and ending with a summary or conclusions.

We are now in a position to implement Gigerenzer¡¯s proposal for revolutionising the way we teach risk. An informed structure and curriculum of the decision-making process could readily be based on the existing literature. For example, the statistical aspects and quantitative presentation of risk are well covered by Gigerenzer and by David Spiegelhalter. Some of the workings of the mind are well understood (as the work of Jonathan Haidt and Daniel Kahneman shows), as are accidents and system behaviour (Charles Perrow, Cass R. Sunstein) and both strategy and risk itself (Lawrence Freedman, John Adams).

Meanwhile, we must all be more risk savvy. Do not assume that the gods will always protect you. Make your own luck. Take care, be thoughtful. Mistrust experts. Distrust vested interests. Do not ride tigers or motorcycles. Avoid gold-diggers. And have a nice day.