Getting risk wrong

This is an edited and abbreviated version of a talk prepared for the 2009 Australian Skeptics national convention. It was delivered as part of a talk I gave to Western Sydney Freethinkers about the public's inability to assess risk and use statistics and numbers

People are notoriously bad at assessing risk. That is, at correctly distinguishing between decisions based on fact and those based on opinion, or to put it another way, decisions based on the head and those on the gut. We tend to overrate some risks and underrate others, often without any apparent logical basis. Much of the work of skeptical organisations and campaigners for critical thinking is generated by this inability to separate emotion from cold hard analysis.

I recently travelled from Sydney to Brisbane by train to attend a conference. I know at least one other person made an interstate train trip but most of the delegates who came from outside Queensland travelled by air. Many of the locals drove to the conference venue.

Most people will be aware of Australia's exemplary record of air travel safety. It is in fact the safest means of transport in Australia, including walking or being pushed in a pram, when calculated by fatal incidents per passenger kilometre. Motor vehicles kill about two thousand Australians each year and around 800 people have died on the road between Sydney and Brisbane in the last two decades. On my train trip I passed through places where more than a hundred people have died in rail accidents over the last few years (Glenbrook, Cowan and Granville).

The surprising thing is that the form of travel most feared by people is going by air, the safest form of all. There is a good business in providing Fear of Flying courses and everyone is worried about the dreadful effects of jet lag and stroke from deep vein thrombosis. Whenever an air crash is reported in the news there are flight cancellations in the ensuing weeks. Contrast this with the fact that despite constant advertising about road safety people continue to drive without seat belts or when intoxicated. The train trip from Brisbane to Sydney takes longer than the plane flight from Sydney to Los Angeles, but I have never heard anyone express concern about deep vein thrombosis on the train.

Part of the problem is a combination of familiarity and what the psychologists call availability. For most people, the frequency of reading about or seeing images of plane crashes is greater than the frequency that they actually get to sit in a plane, and those reports and images are always very graphic, with survival often attributed to a miracle. Car travel, on the other hand, is something we do all the time and even though we see the safety advertisements most people don't know anyone who has been killed in a car. We know from personal experience that car travel is safe so the warnings are ignored. Commuters catch trains ten times a week so again they can use their gut to tell them that train travel is safe. I lived at Penrith at the time of the Granville train crash in 1977 and everybody I knew in the area knew at least one person who died, but we all got back on the train the next day to go to work.

As well as the constant barrage of information about car safety which seems to be ignored there are other well publicised health risks which are widely ignored. Smoking kills ten times as many Australians as cars do but people still smoke, and nobody could be unaware of the dangers of cigarettes. Advertisements on the television are warning us of the danger of skin cancer from tanning but there seem to be tanning clinics in every large shopping centre.

So we have very well publicised dangers which are ignored by a large proportion of the population, but the really strange thing is how the public reacts to dangers which are not publicised by scientists or responsible government authorities but by people with no qualifications or with agendas to promote or books to sell.

The archetypical example of books by unqualified people which exaggerate dangers and yet are readily accepted by large numbers as identifying real risks are diet books. I have in front of me two books (with coincidentally the same title) warning of the dangers of aspartame and fructose respectively. Both have had very good sales and have generated wide public comment and concern about the deadliness of the two chemicals in question, but both are written by authors with no training in either science or nutrition.

Alternative medicine relies on faulty perception of risk for its survival. As an example, I am often told that the fact that a drug is only available on prescription means that it is inherently extremely dangerous, but of the two drugs I carry with me when I travel (metformin and paracetamol) the prescription-only one has no known toxic dose but a deadly amount of the over-the-counter drug can be bought in any supermarket for less than ten dollars.

And don't get me started on the insane campaign to convince the world that vaccines are more dangerous than the diseases they prevent.

Skeptics often try (and fail) to correct people's misconceptions by the application of science and reason. We need to recognise that when decisions are made with the gut rather than the head that another approach is required. One day I hope to work out what this approach might be.

This article was published as the Naked Skeptic column in the February 2010 edition of Australasian Science

A version of this article was published on the Yahoo! 7 News Blog on July 15, 2010

Readers' comments at Yahoo!7

Earlier comments were deleted from the Yahoo!7 site before they could be captured and reproduced here.

Bradish22
04:47pm Monday 11th October 2010 EST

No-one's denying for one second that there can be any possible slant you can think of on statistics and the evidence bore through scientifc scrutiny and reasoning. Just like your view on the IPCC, Stern and Garnau reports. Skeptics is also one slanted and driven, usually by ultra-conservative, religous and economic principles. Not through science.