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International Journal of Epidemiology 2003;32:922-924
© International Epidemiological Association 2003

Symposium

Fisher and Bradford Hill: theory and pragmatism?

Iain Chalmers

James Lind Library, James Lind Initiative, Summertown Pavilion, Middle Way, Oxford OX2 7LG, UK. E-mail: ichalmers@jameslindlibrary.org

Accepted 9 July 2003

The first 150 words of the full text of this article appear below.

During the 1930s, RA Fisher showed how randomization provided the theoretical underpinning for tests of statistical significance.1 Because of this, it is often assumed that Fisher must have played a key role in the evolution of randomized trials in medicine during the 1930s and 1940s. Randomization was adopted by Austin Bradford Hill for Medical Research Council (MRC) trials for a more pragmatic reason, however. Bradford Hill was aware that an alternate allocation scheme had not been strictly observed in a MRC trial done in the early 1930s2 and that selection bias had thus probably undermined the validity of the comparisons made in the study. In designing MRC trials a decade later, he therefore used allocation schedules based on random numbers. If properly concealed, these made it more difficult for those recruiting participants to know which allocations were next in line, and, thus less likely to introduce bias in assembling therapeutic . . . [Full Text of this Article]


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