4.8 Box plots

Box plots are our go to method for quickly visualising summary statistics of a continuous outcome variable (such as life expectancy in the gapminder dataset).

Box plots include:

  • the median (middle line in the box)
  • inter-quartile range (IQR, top and bottom parts of the boxes - this is where 50% of your data is)
  • whiskers (the black lines extending to the lowest and highest values that are still within 1.5*IQR)
  • outliers (any observations out with the whiskers)