Diagram:
A pictorial representation of observed data is called a diagram.
Diagram is self-explanatory in nature and can be easily created and understood by anyone.
Although one needs to make use of scale and measurement to draw a diagram, one does not need to have a thorough knowledge of statistics to draw it.
A diagram is drawn for data having discrete(discontinuous) frequency distribution. For example, the data could be
1 No. of children born in a month,
2 Price in rupees,
3 No. of road accidents, etc.