A note on error bars as a graphical representation of the variability of data in biomedical research: Choosing between standard deviation and standard error of the mean.

Standard deviation and standard error of the mean have been applied widely as error bars in scientific plots. Unfortunately, there is no universally accepted principle addressing which of these two measures should be used. Here we seek to fill this gap by outlining the reasoning for choosing standard error of the mean over standard deviation and hope to shed light on this unsettled disagreement among the biomedical community. The utility of standard error of the mean and standard deviation as error bars is further discussed by examining the figures and plots published in two research articles on pancreatic disease.