Endgames

Statistical quiz

Correlation

BMJ 2009; 339 doi: 10.1136/bmj.b2578 (Published 1 July 2009)
Cite this as: BMJ 2009;339:b2578

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  1. John Fletcher, clinical epidemiologist
  1. 1BMJ, London WC1H 9JR
  1. jfletcher{at}bmj.com

    Which of the following, if any, does not measure correlation?

    • a) Kendall’s τ

    • b) Spearman’s ρ

    • c) Cronbach’s α

    • d) Pearson’s r

    Answer

    None—These are all measures of correlation. Kendall’s τ is a non-parametric measure of correlation that involves measuring the degree of correspondence in rank order between two variables. Spearman’s ρ is also a non-parametric measure of correlation based on rank order. Both methods have …

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