Box plots

Box-and-whisker plots (or boxplots)

These are very basic diagrams used to highlight the quartiles and median to give a quick and clear way of presenting the spread of the data.

1. The 'box' part is drawn from the lower quartile to the upper quartile. The median is then drawn within the box.
2. The 'box' shows the inter-quartile range, which houses the middle half of the data.
3. The 'whiskers' are then drawn to the lowest and highest values of the data.

Firstly, to find the middle value, you will need to find the median of all data presented.

Secondly…