Joined-up quartiles

Box plots are an effective way to compare the distributions of different groups of values. When the groups are ordered, an alternative to the conventional display of the box plots is to join up the medians, quartiles and extremes of the groups in shaded bands.

Monthly rainfall in Samaru, Nigeria

Rainfall is highly seasonal in most of Africa. The diagram below shows monthly rainfalls in Samaru in northern Nigeria between 1928 and 1983 as a jittered dot plot for each month.

Select Box plots from the pop-up menu. Box plots effectively summarise the dot plots in a way that captures the main differences between the months.

Select Box plots and percentile bands from the pop-up menu. Shaded bands now join the monthly median rainfalls and the monthly quartiles and extremes.

Select Percentile bands only to show only the percentile monthly rainfalls. This is a common way to display monthly rainfall data.