The Numbers Game

As statistics proliferate, they unfortunately tend to confuse rather than enlighten. Experts point to a number of ways stats generally drive people batty.

* Ecological Fallacy: Statistics professor Robert Stine of the University of Pennsylvania said this is one way people use statistics as a smoke screen. He pointed to a study in the 1950s that showed that the percentage of crime was highest where the percentage of immigrants was greatest, thus “proving” that immigration caused crime. “In fact, when you looked at individuals, immigrants did almost none of the crimes.” Ecological fallacies thus cause spurious correlations.

* Butterfly Effect: It’s taken from the theory of chaos developed by Edward Lorenz, which tried to describe how a butterfly shaking its wings in Hawaii could cause changes in the weather around the world. In this way, statistics can be extrapolated far out of proportion. Sports is a great venue for this. A batter has a .500 average against right-handed pitchers. Yet maybe only two of his 350 at bats are against right-handers.

* Strained Incidence Rate: In the cell phone cancer scare a few years back, a study showed that six of every 100,000 cell phone users eventually suffered from brain cancer. That sounds very high, but it meant that 600 American cell phone users might get brain cancer in a year, which is a fairly insignificant number.

* Halo Effect: In “A Mathematician Reads the Newspaper” (Basic Books, 1995), John Allen Paulos noted that a statistic takes on a much greater effect if the user has a “halo,” like an Ivy League professorship.

* False Predictors: Stine (with the “halo” of an Ivy League professorship, by the way) says statistics are often used to predict things they can’t. Computer models that claim to predict the weather or the Dow Jones industrial average six months in advance are great for newscasts, but hardly reliable. “I could tell you I have a statistical model where I can predict the gross national product in 2050 by cutting open chickens and counting grains in their stomachs,” Stine said. “That’s safe. No one will be around to check.”