Why Behavior Overshadows Statistics

If we’re sick or injured, we’re generally not satisfied with an explanation such as “These things just happen sometimes.”

A number of psychological studies suggest that we are more liable to attribute the occurrence of an unfortunate event to people rather than to chance, particularly if it is dramatic or has emotional implications.

In one study by psychologist Ed Walster, a group of subjects was told that a man parked his car on an incline and that it rolled down into a fire hydrant after he walked away. Most of the group expressed tolerance and said they had had similar lapses.

Another group was told a slightly altered story in which the car rolled into a pedestrian after the driver walked away. The members of this second group were much more critical of the man’s actions, vilified him, and tended to hold him responsible even though the negligence was the same in both stories.

If things go seriously wrong, we’re predisposed to go looking for someone responsible.

Firestone Tires

Such studies bring to mind dramatic accusations in recent news stories and, in particular, of alleged executive wrongdoing in the Firestone-Ford case. First, let’s note the statistics behind the tire story. The New York Times made the statistical basis of the complaint against Firestone much clearer when it noted that fatal crashes of Ford Explorers, which use Firestone tires, were almost 2.8 times as likely to involve faulty tires as fatal crashes of other sports utility vehicles.

Other ways of looking at the data — and there are many — did not point to any problem with the tires.

This shouldn’t be that surprising for two reasons. First, relationships among variables buried in mountains of data are often hard to find (although, given enough time, data-mining techniques can turn up all sorts of interesting ones, including many that are bogus).

The second reason is the rarity of the crashes. Despite the extensive coverage, which probably suggests to many that treads have been flying off tires left and right, there was, on average, one tire-related fatal crash of a Ford Explorer per 3 billion miles driven. About 100 of the roughly 160,000 automobile deaths during the years 1995 to 1998 were due to faulty tires. In contrast, about 80,000 of the 160,000 automobile deaths during these years involved alcohol. Even driving a lighter-than-average car is one of many vastly more significant risks we assume when we take to the highway.

I certainly don’t wish to exonerate or condemn Firestone and Ford executives, as I have no idea what they knew nor when they knew it. The suggestion, however, that they may have known a lot about the problem early on is what has attracted so much media interest, not the number of deaths themselves. In this regard the story is not different from many others in which human wrongdoing holds much more fascination for people than the relevant numbers.

Bad Doctors, Operators

Consider too the media coverage of last year’s Institute of Medicine report on the inordinate number of deaths due to medical mismanagement. Much of it focused on doctors’ egregious mistakes — amputating the wrong leg, say — and not on the many small changes in the system that could save tens of thousands of lives annually. Again, misbehavior seems to attract more attention than inefficient routines even when the latter kill more people.

A more homely example is provided by a recent news story in Philadelphia about a 911 operator who allegedly diverted business to a private ambulance service. The possible delay in rerouting that was involved may have contributed to the caller’s death, and the story was front-page news for several days.

As I mentioned in a column last year, what hasn’t been front-page news is an unrelated, but much more important ambulance story: The fact that automatic external defribillators are deployed in only half of all ambulances and fewer than 1 percent of emergency police and fire vehicles. The Red Cross and emergency personnel estimate that the broad deployment of these inexpensive portable devices could save thousands of lives in the United States annually.

A Puzzle In our reaction to these and countless other stories we are probably responding in very natural ways. Probability and risk assessment don’t register easily with people, whereas misbehavior does. There’s even a classic psychological experiment that underscores our sensitivity to law-breaking.

The psychologist Peter Wason demonstrated that most subjects are not very good at the following task: Four cards, each with a number on one side and a letter on the other, are displayed on a table. The subject is asked which cards he must turn over to confirm the statement: If a card has a D on one side, it has a 3 on the other. The four cards before him have, respectively, a D, F, 3, and 2 facing up. Wason found most people incorrectly turn over the D and 3 cards instead of the D and 2. (If the 2 has a D on the other side, it disproves the statement. A 3 with a different letter on the other side does not.)

Contrast this task with another one involving a possible social infraction. A bouncer at a bar must throw out underage drinkers. He’s confronted with four people: a beer drinker, a cola drinker, a 28-year-old, and a 16-year-old. Which two should he interrogate further? Here it’s clear to almost everyone that it’s the beer-drinker and the 16-year-old who must be interrogated.

But this problem is logically equivalent to the first one! (What a person is drinking is “one side” of him, his age is the other, and the bouncer must confirm the statement: If a person is drinking alcohol, then he is over 18.)

For better or worse, we often seem to be more responsive to particular wrongdoings than to the general well-being.

Professor of mathematics at Temple University, John Allen Paulos is the author of several best-selling books, including Innumeracy and A Mathematician Reads the Newspaper. His Who’s Counting? column on ABCNEWS.com appears on the first day of every month.