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Lancet. 1990 Jan 20;335(8682):149-53.

Randomisation and baseline comparisons in clinical trials.

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Medical Statistics Laboratory, Imperial Cancer Research Fund, London, UK.


80 reports of randomised clinical trials in four leading general medical journals were reviewed. The reporting of the methodology of randomisation was inadequate. In 30% of trials there was no clear evidence that the groups had been randomised. Among trials that used simple randomisation the sample sizes in the two groups were too often similar, and there was an unexpected small bias in favour of there being fewer patients in the experimental group. The handling of comparisons of baseline characteristics was inadequate in 41% of the trials. Suggestions are made for improving standards.

[Indexed for MEDLINE]

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