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

TLDR

Correlation is a simple statistical method used to assess linear associations between two continuous variables, yet its misuse is widespread among researchers. The article aims to guide appropriate use of correlation in medical research and highlight common misuses. The authors illustrate correlation applications through simulated and real data examples. They provide a rule‑of‑thumb for interpreting correlation magnitude.

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.