Intended for healthcare professionals

Endgames Statistical Question

Stratified cluster sampling

BMJ 2013; 347 doi: (Published 22 November 2013) Cite this as: BMJ 2013;347:f7016
  1. Philip Sedgwick, reader in medical statistics and medical education
  1. 1Centre for Medical and Healthcare Education, St George’s, University of London, London, UK
  1. p.sedgwick{at}

Researchers investigated the suitability of a newly developed famine scale as an international definition of famine to guide humanitarian response, funding, and accountability.1 The scale had been proposed by Howe and Devereux, and it defined famine on the basis of intensity and magnitude.2 The scale was applied retrospectively to the humanitarian crisis during 2005 in Niger, west Africa, to determine whether famine had occurred. A cross sectional study design was used. Households were recruited using a stratified two stage cluster sampling method. Niger was stratified into its eight regions. Within each region, 26 villages were randomly selected, with the probability of selection proportional to the size of the village. Within each village, 20 households were systematically randomly selected. A census of the entire household was undertaken by administering a questionnaire to the head of each selected household.

The researchers concluded that on the basis of the famine scale developed by Howe and Devereux, most regions in Niger in 2005 experienced food crisis conditions, and some areas approached famine. Furthermore, it was suggested that the scale afforded more objective criteria than did previous approaches while providing early warning systems that might help guide the level of response in future situations.

Which of the following statements, if any, are true?

  • a) Cluster sampling meant that resources could be concentrated in a limited number of areas of the country

  • b) The stratified two stage cluster sampling approach constituted a multistage sampling method with …

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