Bar plot without grouping variable

Question

This seems like to simplest thing to do, but I have not been able to figure this out on R. For descriptive purposes, I want to create one bar graph that show the means and error plots of multiple questions/variables. My data is based on anonymous responses so there is no grouping variables.

Is there a way to do this on R? Below is an example of what my data looks like. I would like to plot mean and standard deviation of each variable next to each other in the same bar graph.

dat <- data.frame(satisfaction = c(1, 2, 3, 4),
                  engaged = c(2, 3, 4, 2),
                  relevant = c(4, 1, 3, 2),
                  recommend = c(4, 1, 3, 3))

Answer 1

What you could do is reshape the data into long format with reshape2 (or data.table or tidyr) without specifying an id-variable and using all columns as measure variables. After that you can create a plot with for example ggplot2. Using:

library(reshape2)
library(ggplot2)

# reshape into long format
dat2 <- melt(dat, measure.vars = 1:4)  # or just: melt(dat)

# create the plot
ggplot(dat2, aes(x = variable, y = value)) +
  stat_summary(geom = 'bar', fun.y = 'mean', width = 0.7, fill = 'grey') +
  stat_summary(geom = 'errorbar', width = 0.2, size = 1.5) +
  theme_minimal(base_size = 14) +
  theme(axis.title = element_blank())

gives:

---

Update: As @GavinSimpson pointed out in his answer: for visualizing means and standard errors, a barplot is not the best alternative. As an alternative you could also use geom_pointrange:

ggplot(dat2, aes(x = variable, y = value)) +
  stat_summary(geom = 'pointrange', fatten = 5, size = 1.2) +
  theme_minimal(base_size = 14) +
  theme(axis.title = element_blank())

which gives:

Answer 2

Whilst I know you asked for a barplot, a dotplot of the data is an alternative visualisation that focuses on the means and standard errors. If the drawing of a bar all the way to 0 is not that informative, the dotplot is a good alternative.

Reusing the objects and code from @Procrastinatus Maximus' answer we have:

ggplot(dat2, aes(x = variable, y = value)) +
  stat_summary(geom = 'point', fun.y = 'mean', size = 2) +
  stat_summary(geom = 'errorbar', width = 0.2) +
  xlab(NULL) + 
  theme_bw()

which produces