Intended for healthcare professionals

Endgames Statistical question

Choosing a statistic

BMJ 2009; 339 doi: (Published 08 July 2009) Cite this as: BMJ 2009;339:b2702
  1. John Fletcher, clinical epidemiologist
  1. 1BMJ, BMA House, Tavistock Square, London WC1H 9JR
  1. jfletcher{at}

    Which statistical test is best for each outcome measure?

    Outcome measure

    • a) Comparing improvement in pain scores over 4 weeks using a visual analogue scale in a trial of 100 people with back pain.

    • b) Comparing the effect of two drugs on time to reduce fever below 38ºC in two groups of 100 febrile infants.

    • c) Comparing for 100 countries the number of doctors trained per million population with the infant mortality rate of that country.

    • d) Comparing death rates at 30 days after discharge from hospital of 100 patients having hip surgery and 100 patients having eye surgery.


    • e) Chi square test (χ2) …

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