How Corporations and Politicians Use Numbers to Lie — and How Not to Be Fooled

Do 8 out of 10 dentists really prefer Colgate?

By Larry Schwartz

Americans, as P.T. Barnum once noted, are not all that difficult to fool, and our nation’s somewhat weak math skills don’t help. A Pew Research Center report issued last year, which studied test results of 15-year-olds, ranked the United States 35th in the world in math. Not only has this weakness in understanding numbers created opportunities for mass exploitation by Big Pharma and other industries, it has led to needless and mostly unwarranted fear. While Americans don’t understand math, be assured that corporations do, and they happily use it to mislead and obfuscate in the name of selling their products.

Big Pharma doesn’t only target consumers with its misleading advertising; it also targets your doctor. And why not? Sadly, a medical degree doesn’t necessarily mean your doctor is a numbers whiz. In a report in the journal Psychological Science in the Pubic Interest on doctors’ ability to analyze relevant statistics, they were asked, “If my mammogram is positive, what are the odds that I actually have cancer?” Doctors were given all the information needed to answer that question accurately, and a startling number of them still got it wrong. In fact, only 20 percent of them got it right. (The answer, by the way, is a 10 percent chance.) Of those who got it wrong, 60 percent erred drastically on the side of doom, saying the chances of having cancer were 80 to 90 percent. So if your doctor was in that group, and you got a positive mammogram result, she would have told you that you almost certainly have cancer.