Lightning strike twice? It hit me SEVEN times!
POPULAR SCIENCE THE IMPROBABILITY PRINCIPLE
DuRINg the summer of 1972, actor Anthony Hopkins was offered a leading part in a film of george Feifer’s novel The girl From Petrovka.
He went to London to buy a copy, but trawled all the bookshops without finding one. giving up, he was waiting for the Tube at Leicester Square when he noticed a discarded book on the seat next to him: The girl From Petrovka.
That’s weird enough, but some time later he met Feifer and told him the story. Feifer said that in November 1971 he’d loaned a friend a copy of the book, one containing his own notes for turning the language from British English into American.
The friend had lost the copy in Bayswater, West London. When Hopkins checked, it proved to be the same book.
The mind boggles at calculating the chances of that happening and yet, argues mathematician David Hand in his intriguing new book, events like this, with a seemingly very remote probability, keep occurring.
Various reasons support this theory. One i s the l aw of truly large numbers. This can be illustrated by looking for a fourleafed clover. Clover usually has three l eaves, but one in 10,000 has four. Faced with this statistic, it’s a wonder anyone ever finds one, but people do, and fairly frequently, too.
What you have to consider is the number of people who might look for one. If 1,000 people (think of all those children who try it) look at just ten clovers each, someone should find a four-leafed one.
A misunderstanding of statistics can make events appear more incredible than they really are. For example, the odds of being struck by lightning are one in 300,000. But Roy Sullivan, a park ranger in Virginia, was struck by lightning seven times, between 1942 and 1977, incurring various injuries, none serious.
All seven strikes were confirmed by the park’s superintendent and doctors. On the face of it, Roy’s experiences seem i mpossible unless someone up there had it in f or him — until you remember that one in 300,000 is an average. Most people live in cities, surrounded by high buildings where virtually no one ever gets struck by lightning. For the majority of people’s chances of being hit to be so low, someone, somewhere, must be getting more than their fair share of heavenly hits. Considering t his, it’s less surprising that a man whose job was wandering around in open countryside recorded several strikes over 35 years.
Lotteries throw up interesting ideas about probability. Your chances of winning the National Lottery are one in 14 million. Yet we continue to buy tickets week after week, inspired by the fact someone hits the jackpot, and ignoring the other fact that the odds are overwhelmingly against it being us.
After all, you hear of amazing pieces of Lottery luck, for example people who hit the jackpot twice, or ironically bad luck, like the woman i n America who bought tickets for two different state lotteries.
She got both the winning numbers right — unfortunately, each correct line was on the ticket for the other lottery.
While these stories seem fantastically unlikely, you need to remember the tens of millions of people worldwide who regularly enter lotteries. In that context it’s perhaps amazing such anecdotes don’t surface more often.
Sometimes events can seem incredible because we alter the parameters with hindsight. A British man and his wife each escaped unhurt from different fatal train crashes 15 years apart. Extremely unlikely.
But suppose we apply the law of ‘near enough’ not just to spouses, but children, parents, cousins or aunts and uncles. We’re likely to find many more ‘amazing’ coincidences.
We are all too keen to ascribe events to luck and see rare events as miraculous, because we don’t understand how numbers work.
NOWHERE is this truer than the so-called gambler’s fallacy. The odds of a tossed coin coming up heads or tails are even. But suppose you throw six heads in a row. The fallacy leads us to think that for the odds to come out even, the next six throws have to be tails.
You can apply this to card games or roulette. But it doesn’t work like that. What happens is something called ‘regression to the mean’, where the results of cumulative throws gradually restore the results to even, so over the next 100 throws, or maybe a thousand, tails will come up slightly more often until the balance reaches 50-50 again.
If you’re someone who likes a flutter, it might be an idea to look at Hand’s book before you risk your money. For the rest of us it’s a hugely entertaining eye-opener as to how misuse of statistics can skew our view of the world.