Internal validity of trials is more important than generalisability

BMJ 1996; 312 doi: https://doi.org/10.1136/bmj.312.7033.779a (Published 23 March 1996) Cite this as: BMJ 1996;312:779
  1. Jonathan Mant,
  2. Martin Dawes,
  3. Susanna Graham-Jones
  1. Clinical lecturer in public health medicine General practitioner Lecturer in general practice Department of Public Health and Primary Care, University of Oxford, Radcliffe Infirmary, Oxford OX2 6HE

    EDITOR,—Mike Pringle and Richard Churchill raise important issues relating to the practicalities of performing and interpreting the results of randomised controlled trials in general practice.1 They suggest that observational studies are acceptable when a randomised study is too difficult to perform or when its results will be clinically meaningless, reminding us of the complementary (rather than competing) roles that experimental and observational methods should have in the evaluation of health care interventions.2 We are concerned, …

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