Control groupsBMJ 2010; 340 doi: https://doi.org/10.1136/bmj.c391 (Published 28 January 2010) Cite this as: BMJ 2010;340:c391
- Philip Sedgwick, senior lecturer in medical statistics
- 1Centre for Medical and Healthcare Education, St George’s, University of London, Tooting, London SW17 0RE
Researchers undertook a randomised controlled trial to assess the effect of zinc supplementation on the severity and duration of diarrhoea caused by cholera in children.1 Children were recruited if they had watery diarrhoea and dark field examination of stool was positive for Vibrio cholera (confirmed by stool culture). Children were randomly allocated to zinc supplementation or placebo. Zinc supplementation was found to reduce the duration and severity of diarrhoea in children with cholera.
Which of the following statements, if any, are true?
a) The control group comprised children without diarrhoea