How to add standard error bars to a box and whisker plot using ggplot2?

Question

I\'m trying to add standard error bars to my data similar to the ones seen on the box plots near the end of the answer on this question: https://stats.stackexchange.com/question

Answer 1

There is a mean_se function in ggplot2 which does exactly what you want.

library(ggplot2)
ggplot(PlantGrowth, aes(group, weight))+
  stat_boxplot( aes(group, weight), 
    geom='errorbar', linetype=1, width=0.5)+  #whiskers
  geom_boxplot( aes(group, weight),outlier.shape=1) +    
  stat_summary(fun.y=mean, geom="point", size=2) + 
  stat_summary(fun.data = mean_se, geom = "errorbar")