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Education And Debate

Statistics Notes: Presentation of numerical data

BMJ 1996; 312 doi: (Published 02 March 1996) Cite this as: BMJ 1996;312:572
  1. Douglas G Altman, heada,
  2. J Martin Bland, professor of medical statisticsb
  1. a IRCF Medical Statistics Group, Centre for Statistics in Medicine, Institute of Health Sciences, PO Box 777, Oxford OX3 7LF
  2. b Department of Public Health Sciences, St George's Hospital Medical School, London SW17 0RE
  1. Correspondence to: Mr Altman.

    The purpose of a scientific paper is to communicate, and within the paper this applies especially to the presentation of data.

    Continuous data, such as serum cholesterol concentration or triceps skinfold thickness, can be summarised numerically either in the text or in tables or plotted in a graph. When numbers are given there is the problem of how precisely to specify them. As far as possible the numerical precision used should be consistent throughout a paper and especially within a table. In general, summary statistics such as means should not be given to more than one extra decimal place over the raw data. The same usually applies to measures of variability or uncertainty such as the standard deviation or standard error, though greater precision may be warranted for these quantities as they are …

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