Intended for healthcare professionals

Endgames Statistical question

Factorial trials

BMJ 2010; 340 doi: (Published 30 June 2010) Cite this as: BMJ 2010;340:c3401
  1. Philip Sedgwick, senior lecturer in medical statistics
  1. 1Centre for Medical and Healthcare Education, St George’s, University of London, Tooting, London SW17 0RE
  1. p.sedgwick{at}

    Researchers investigated the effects of two separate interventions—dietary advice and knee strengthening exercises—on knee pain and function using a pragmatic factorial randomised controlled trial of two years’ duration.1 Trial participants were overweight or obese adults in the community recruited at their general practice. The dietary intervention consisted of individualised advice on healthy eating. The knee strengthening exercise intervention was a home based self managed programme. For both interventions, the control arm was an advice leaflet based on the Arthritis Research Campaign (United Kingdom) leaflet for osteoarthritis of the knee.

    Which of the following, if any, are true?

    • a) The trial permitted the simultaneous investigation of dietary advice and …

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