Intended for healthcare professionals

Endgames Statistical Question

Random allocation I

BMJ 2009; 339 doi: (Published 19 November 2009) Cite this as: BMJ 2009;339:b4719
  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}

    A randomised single blind controlled trial investigated whether pelvic floor muscle training during pregnancy prevented urinary incontinence during and after pregnancy. The trial recruited healthy nulliparous women when they attended their first routine ultrasound. After giving informed consent, women were randomly allocated to the training group or control group.1

    Which one of the following statements defines the process of random allocation used above?

    • a) For every woman allocated to the training group, a woman of the same age was allocated to the control group

    • b) Women were allocated alternately to the training or control group

    • c) Women were allocated to the clinician’s group of choice

    • d) Women had an equal probability of …

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