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. 2012 Sep;24(3):69-71.

Statistics corner: A guide to appropriate use of correlation coefficient in medical research

M M Mukaka  1
Affiliations

Statistics corner: A guide to appropriate use of correlation coefficient in medical research

M M Mukaka. Malawi Med J. 2012 Sep.

Abstract

Correlation is a statistical method used to assess a possible linear association between two continuous variables. It is simple both to calculate and to interpret. However, misuse of correlation is so common among researchers that some statisticians have wished that the method had never been devised at all. The aim of this article is to provide a guide to appropriate use of correlation in medical research and to highlight some misuse. Examples of the applications of the correlation coefficient have been provided using data from statistical simulations as well as real data. Rule of thumb for interpreting size of a correlation coefficient has been provided.

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Figures

Fig. 1
Fig. 1
Scatterplot of x and y: Pearson's correlation=0.2
Fig. 2
Fig. 2
Scatterplot of x and y: Pearson's correlation=0.50
Fig. 3
Fig. 3
Scatterplot of x and y: Pearson's correlation=0.80
Fig. 4
Fig. 4
Scatterplot of x and y: Pearson's correlation=−0.80
Fig. 5
Fig. 5
A scatter plot of haemoglobin against parity for 783 women attending ANC visit number 1
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