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The Norm Chronicles

Michael Blastland and David Spiegelhalter
Basic Books
Publication Date: 
Number of Pages: 
[Reviewed by
Mark Bollman
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Meet the characters in this mathematical drama:

Prudence: possibly the most risk-averse person possible; a trait inherited at birth.

Norm: a man who is “average” on every measure of humanity–and thus very very unusual.

Kelvin, Kevin, and Kieran, the Kevlin brothers: the risk-takers of the crew.

This highly entertaining and informative look at risk plays itself out over the course of a lifetime, and taps into each of these three reactions to probability in the service of risk to deliver its message. Each chapter begins with a brief vignette starring one or more of these characters in an illustration of risk and then proceeds to give an intricate non-technical explanation of the principles involved, from infancy and vaccinations through extreme sports and radiation, until medical issues surface near the end of life.

The book’s appeal lies in no small part to its use of the “MicroMort” as a unit of measurement for assessing risk. One MicroMort (MM) corresponds to an increased chance of death of one in one million. In America, just going through daily life carries a risk of death from natural causes of 1 MM per day if homicide and suicide are excluded as causes of death. This is equal to the increased risk of driving 240 miles, flying 7500 miles on a commercial aircraft, or of dying via asteroid strike in your lifetime.

This, of course, is merely an average, represented by the character Norm. With this framework established, a meaningful comparison of the risk from other causes is possible, and the authors explain these causes in impressive detail and yet with proper attention to mathematics.

Mark Bollman ( is professor of mathematics and chair of the department of mathematics and computer science at Albion College in Michigan. His mathematical interests include number theory, probability, and geometry. Mark’s claim to be the only Project NExT fellow (Forest dot, 2002) who has taught both English composition and organic chemistry to college students has not, to his knowledge, been successfully contradicted. If it ever is, he is sure that his experience teaching introductory geology will break the deadlock.

The table of contents is not available.