Should people take the beaten path or follow the capricious road-map dots plotted on a whim? Should a khaki-wearing Ivy Leaguer ask out the girl with the full-sleeve tattoo? And should someone give into the lure of the money pot of the Strip, uncertain of his wallet’s fate?
For decisions like these, Jeffrey Rosenthal, a statistics professor at the University of Toronto, suggests using probability theory, or mathematical reasoning, to determine the likelihood of a certain outcome. In his book Struck by Lightning: The Curious World of Probabilities, he uses simple math and amusing anecdotes to explain how we might use this tactic to make better sense of seemingly random, everyday events, which he says are actually governed by probability. Rosenthal, a Harvard grad, addresses his theory in a Feb. 18 lecture at UNLV’s Marjorie Barrick Museum of Natural History.
“When it comes to probabilities and randomness, if you’re stopping and thinking if something is worth worrying about it, it’s half the battle won,” he says. “There are times where you can’t work out the exact probability, but you can think about whether things are more likely to happen.”
A large chunk of his book hits home for Las Vegans, as he explains that casino bets are an ultimate test in using probabilities for decision making. Say someone wants to double his or her first $100 playing craps with $10 bets. That person has a 43 percent chance, Rosenthal says. But should that person go on, keeping up with the six-shooter across the way who’s trying to go double on $10,000? In terms of probability, “You’re more likely to die in an accident on the way to the casino than to achieve that,” he says.
Rosenthal chalks up the fact that casinos always win to the Law of Large Numbers, a theory that says if a game is even slightly to your disadvantage, and you play long enough, you’ll come out behind. He explains that casinos maintain a profit margin between 1 percent and 3 percent of the total amount of money bet.
And we’re not the only ones using probability to make decisions. E-mail spam filters use probabilities, combing through “safe” and “unsafe” words, to determine whether to block a message, Rosenthal says. In his book, he cites Paul Graham’s article “A Plan for Spam” and mentions a few words with high spam-probability: “sexy,” “guarantee,” “madam” and ff0000 (the HTML code for the color bright red).
Besides life’s instances of everyday probabilities, the book addresses people’s heightened sense of fear about events that are extremely unlikely to occur. Should you avoid flying because you’re worried about hijackers? Nah, more people are killed by a spouse each year than died on 9/11, Rosenthal says. And what about the book’s namesake—being struck by lightning? The chances, he says, are about one in six million.
So why do we pay any mind to these things that have a low probability of happening at all? “We’re not mathematical-based people,” explains UNLV psychology professor David Copeland. “What we do is give a lot of importance or weight to things that are very salient or vivid.” He says people overestimate the likelihood of larger-than-life events, such as a terrorist attack or winning a high-stakes game. “People really remember when they win. The slot machines flash lights and sirens go off, and everyone cheers at the roulette table. But when you lose it all kind of blends in together.”
Copeland says the book’s premise of providing context for random events has potential for people who struggle with decisions or anxiety. “If you really educate someone,” he says, “I think people will be a little bit more real about things.”