Saturday, June 22, 2013

By the Numbers

Pick up a paper, watch a news program or read a magazine, and there's likely a headline with a number in it. And not just a number, but a statistic. From the Wall Street Journal: "People With Disabilities Face 13.4% Unemployment Rate." From NBC News: "Cutting CT Scans in Kids Could Reduce Cancer Risk by 62%." From the New York Times: "Global Ticket Sales for Movies Rise 6%." There is virtually no field that can't be sliced, diced and quantified by a stat. From Fine "Blame It On The Guacamole: Avocado Consumption Is Up 100% Over 6 Years."

But what do those numbers really mean? Obviously many people with disabilities do find work, many kids have CT scans without getting cancer and not all movies do better at the box office. As for you, are you really eating twice as much guacamole? Do you even like guacamole? These kinds of questions fascinated both Michael Blastland and David Spiegelhalter. The former is an author, journalist and BBC Radio 4 broadcaster, while the latter is a Professor of Public Understanding of Risk at the University of Cambridge. And they've laid it out, in a fashion, in "The Norm Chronicles."

In it we meet, well, Norm. Norm is 31, 5 feet 9 inches, just over 182 pounds and works a 39 hour week. He likes a drink, doesn't do enough exercise and occasionally treats himself to a bar of chocolate, preferring milk over dark. He's also a married parent, and drives a Ford Fiesta. Norm isn't just average: Norm IS the average. Along with his two friends, Prudence (who is scared of her own shadow) and Kelvin, (who tells Norm where to shove his statistics), they wander through life where everything is a choice based the interplay between risk and chance. Should I fly or take the train? Have a baby? How about a drink? What harm could another sausage do? These are questions Norm, Prudence and Kelvin each face every day, as do you. Even if you don't like sausage.

The trick is that the answers, in the form of statistics, have to be tempered by what you know to be true. After all, the stats say that the average person has 1.9999 legs. In that vein, as the authors point out, most accidental infant deaths occur within the parental home. That means that a parent truly concerned about his or her child's safety should leave them outdoors at all times. Likewise, not feeding them also substantially reduces the possibility of them getting a fatal dose of salmonella. Or in Norm's case, he notes that most murders are committed by people known to the victim. His answer? Have no friends.

Since the numbers can get overwhelming, they quantify much of Norm's adventures in a unit called MicroMorts, or MMs. An MM is a "one-in-a-million chance of something horribly and fatally dramatic happening to Mr. or Ms. Average on an average day spent doing their average, everyday stuff. One MicroMort, in other words, is a benchmark for living normally." A more concrete way of looking at it: "A MicroMort can also be compared to a form of imaginary Russian roulette in which 20 coins are thrown in the air. If they all come down heads, the subject is executed. That is about the same odds as the one-in-a-million chance of the average everyday dose of acute fatal risk."

Using this yardstick, it's easier to compare apples-to-apples. For example, the risk of death from a general anesthetic in a non-emergency operation in the UK is roughly 1 in 100,000. Converted to MircoMorts means that dying from anesthesia has a value of 10 MM, or 10 times the ordinary average risk of getting through the day without a violent or accidental death. Skiing has a value of 1MM, meaning schussing down the slopes has about the same value as getting killed tomorrow. Compare that to riding a motorcycle 28 miles (4MMs), scuba diving (7MM's) or walking 27 miles (1MM).

Of course, risk and chance are not the same thing. One in a million is a long shot. But the "one" does happen. Norm, skittish Prudence and reckless Kelvin each spot a bag in the Tube. Prudence has them evacuate the station. Kelvin opens it and finds a laptop. But Norm? Norm it ignores it, until it blows up; sadly for him, it was a bomb. What are the chances of that? You'll have to read the book to find out.


Marc Wollin of Bedford loves numbers. His column appears regularly in The Record-Review, The Scarsdale Inquirer and online at, as well as via Facebook, LinkedIn and Twitter. 

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