Bar charts

A bar chart, like a frequency diagram, shows the frequency of events occurring. The height of the bar is the frequency.

A simple bar chart may look like this.

Number of customers vs frequency bar chart

Composite bar charts

Bar charts may be needed to compare data.

The following frequency table shows information for the numbers of pets owned by a class.

0 pets1 pet2 pets3 or more pets
Boys2423
Girls3321

A composite bar chart can show this information. A key that shows which bar represents which data is necessary to be able to read the bar chart properly.

Number of pets owned vs frequency bar chart