Monthly rainfall in Samaru, Nigeria, 1928 to 1983
The jittered dot plots show too much detailed information. When box plots are shown, the display is simplified, allowing the seasonal pattern in rainfall to stand out.
A similar example is the rice yields data set at the start of this section.
Rainfall is highly seasonal in most of Africa and its timing and amount is critical for agriculture. The diagram initially shows monthly rainfalls in Samaru in northern Nigeria between 1928 and 1983 as a jittered dot plot for each month.
The box plots highlight the seasonal pattern in the rainfall but the medians and quartiles are useful values in their own right. For example,
You can also comment on the fact that 3/4 of the years had no rainfall in Nov, Dec, Jan and Feb so the lower quartiles, medians and upper quartiles are all zero in these months.