How to do it...

We proceed as follows to add notches and jitters to box plots:

1. Load the packages and use boxplot.stats() to separate the outliers:

> library(ggplot2) ; library(car)
> out_data <- Salaries[match((boxplot.stats(Salaries$salary))$out,
                             Salaries$salary),]

1. Add geom_jitter() along with geom_boxplot() to draw a box plot with jittered outliers:

> set.seed(50)
> box1 <- ggplot(Salaries, aes( x = rank, y = salary))
> box1 + geom_boxplot( notch = T, outlier.shape = NA ) +
    geom_jitter( data = out_data, height = 0, width = .2)

Following, figure 3.2 shows a notched box plot with jittered outliers:

 Figure 3.2 Notched and jittered box plot

Move on to the next section for explanations.