Science & Nature: Statistical Analysis Established That Smoking Led to Lung Cancer. Statistics Save Lives

Article excerpt

To suggest that "there are lies, damn lies and statistics" is really outrageously unfair and misleading. Statistical analysis is fundamental to careful interpretation of data in many areas of science, technology and public affairs. It is essential to the unravelling of complex dependencies. In particular, it is fundamental to the study of many aspects of human health.

Children at school should be taught the importance of randomised clinical trials, an essentially statistical idea, which are vital to the establishment of the effectiveness of treatments. Anecdote will not do in these matters. In the 1940s, Bradford Hill and Richard Doll were investigating the incidence of lung cancer and expected to find air pollution to be of primary importance. But after careful statistical analysis, they established that smoking was the overriding factor. Statistics save lives.

The career of the statistician David Cox illustrates improbabilities in life. He went up to Cambridge during the Second World War to study mathematics. He would have preferred physical chemistry but the headmaster of his grammar school in Birmingham, himself a mathematician, virtually insisted that Cox read mathematics. After two years of exemption from national service, he was sent by the recruiting board to the Royal Aircraft Establishment where he worked on statistical quality-control of aircraft components and the statistical distribution of stresses on aircraft in flight.

In particular, he had to study the strengths of spot-welded joints. If two pieces of metal are welded together with 10 spots, then, under load, perhaps two of the spots may fail but the remaining eight may be strong enough to deal with the enhanced load. In other words, what is the relation between the distribution of strengths of the spots and of the joint? Cox produced a crude solution to this problem in the mathematics of applied probability.

One day, in the library, he read a paper by Henry Daniels giving an elegant solution to the same problem, this time, however, in a textile setting relating the strength of a bundle of fibres to that of the individual fibres. Cox was so impressed that he applied to work with Daniels, the wisest scientific decision he ever made, he now feels. …