The Norm Chronicles
Stories and Numbers about Danger
by Michael Blastland and David Spiegelhalter
Published by Profile Books www.profilebooks.com
Wow! What are the chances of that? Well, according to Blastland and Spiegelhalter, for any given ‘that’, the chances are that you don’t know what the chances are.
In a rather unusual move the authors have put their conclusions in the introduction so I don’t feel I’m being too spoilery sharing them here; for people, probability doesn’t exist. They spend the rest of the book examining just why that is and what we may be missing.
Now, a book on statistics might sound a little dry. Even the authors suggest ‘dipping’ but they do themselves something of a disservice as their eminently readable style is breezy with a touch of black humor and the content is intriguing. Putting a human face on the numbers are three characters: devil-may-care Kelvin, paranoid Pru and Norm, our exactly average hero who always calculates the odds. We follow the friends from birth to death as each chapter opens with a brief vignette illustrating a different period in their lives and the risks they (and we) face in everything from crime to drugs to lifestyle to unemployment etc.
While I can’t argue with Blastland and Spiegelhalter academic qualifications (Eng. Lit radio producer and statistician – self proclaimed “so geeky our anoraks have two hoods”) their mastery of narrative structure leaves a bit to be desired. While a couple of these vignettes are clever, most are awkward if not downright confusing and really could have benefited from a firmer editing hand.
Along with our trio we’re also introduced to the standard ‘Micromort’ – a one-in-a-million chance of death and a ‘Microlife’ – one of a million half hour segments that comprise (roughly) the average life expectancy.
So you run a 1 Micromort risk per 7,500 miles of commercial flying, 7 per marathon run and a whopping 1,020 per year if you are a commercial fisherman. On the other hand 20 minutes of moderate exercise gains you 2.2 Microlives and that first drink of the day gains you 1.1 (though subsequent drinks loose you .7 each). The authors don’t take their estimates too seriously and neither should you but both are handy common denominators to roughly estimate disparate risks and benefits.
Of course there are lies, damned lies and… well, you get the picture and The Norm Chronicles are worth buying just for the insights into how the media manipulate statistics for impact. “Daily Fry-Up increases pancreatic cancer risk by 20%” was a Daily Express headline. Scary enough to put you off sausages for life. Slightly less scary when you know that five people in 400 develop pancreatic cancer anyway in their lifetimes so a 20% risk means one extra person in the 400 will succumb. A lifetime of sausages will change your chance of being just fine from 396/400 to 395/400. Not much of a headline. As the authors point out – it’s all in the framing.
You can’t blame the media too much though; people are designed to put more weight on anecdote then evidence. We care more about what happens to the 5% than what doesn’t happen to the 95%. No news is, after all, no news but it means we vastly overestimate the occurrence of conspicuous risks and ignore mundane threats. Asthma kills many more people than tornadoes, murderers or plane crashes but it doesn’t make good TV.
So, next time you’re walking out of the corner shop with your lottery ticket in hand and wondering what you’d do with the jackpot don’t get too excited. You’re more likely to die before the draw takes place than win it.
It could be you – but it probably won’t be.