Plotting error bars with R

Error bars may show confidence intervals, standard errors, and standard deviations. Each feature conveys a different message and this paper on error bars in experimental biology explains it very nicely. For this post I will demonstrate how to plot error bars that show the standard error (SE) or standard error of the mean (SEM). I found two nice resources that demonstrate the plotting of error bars with R and in this post I illustrate them with simple examples. The first method is from the website of James Holland Jones, where he wrote an R function that plots arrows to a bar plot.

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