The risk factor

Our daily lives are full of dangers, form driving our cars to cholesterol in our food. But how good are we really at assessing these risks?

Not very good at all, according to Steven Levitt and Stephen Dubner in their best selling book Freakonomics. Parents, they say, take danger very seriously but they often worry about completely the wrong things. The authors give as an example the fictional case of a little girl they call 'Molly'. Her parents know that the father of one of her friends keeps a gun in their house, so they decide that Molly is not allowed to play there. Instead, they feel that Molly would be much safer spending time at another friend's house, where there are no guns, but there is a swimming pool. You may think this is the right choice, but according to the statistics, you would be wrong. Every year, one child per 11,000 priyate swimming pools is drowned in the United States. Howeyer , only one child is killed by a gun for every million guns. This means that a child is 100 times more likely to die in a swimming accident than because of playing with a gun.

Molly's parents are not unique. Generally people are just not very good at assessing risk. Peter Sandman, a risk consultant at Princeton University, New Jersey, says `The risks that scare people and the risks that kill people are very different things.' He compares the dangerous bacteria in our kitchen and diseases such as mad cow disease: the first is very common, but for some reason not very frightening; the second is extremely rare, but it terrifies us. 'Risks that you can control are much less worrying than risks you can't control,' says Sandman. 'We can't tell if our meat is infected, whereas we can control how dean our kitchen is.'

This 'control factor' probably explains why flying tends to scare people more than driving. Levitt argues, 'Their thinking goes like this: "since i control the car, I am the one keeping myself safe; since I have no control of the aeroplane, I am at the mercy of external factors."' Actually, the question of which is more dangerous is not as simple as many people think. Statistics for the United States show that, although many more people die each year in mad accidents than in piane crashes, driving isn't necessarily more dangerous. This is because generally people spend far less time flying than driving. In fact, statistically, the number of deaths for each hour of driving compared with each hour of flying is about the same. So flying and driving carry a very similar risk. It is just our lack of control when flying that makes it seem more scary.

Levitt also says that people tend to be much more scared of short-term dangers than long-term ones. The probability of someone being killed in a terrorist attack is infinitely smaller than the probability that this same person will eat too much fatty food and die of heart disease. 'But a terrorist attack happens now,' says Levitt. 'Death from heart disease is a distant, quiet catastrophe. Terrorist acts lie beyond our control — French fries do not.'

Finally there is what Peter Sandman calls 'the dread factor', that is how horrific we consider something to be. We are horrified by the thought of being killed in a terrorist attack, but for some reason we are not horrified by the thought of death from heart disease. Sandman uses the following equation: for most people risk = hazard (or danger) + outrage (or horror). 'When the hazard is high but the terror is low, people underreact. When the hazard is low and the outrage is high, people overreact.' Which is why so many parents will do more to protect their children from a gun accident than from a swimming pool accident. A gun horrifies us, but a swimming pool does not.