Statistics » Bar chart / Histogram

What is a bar chart?

A bar chart is a schematic representation of data in using bars.
Below you can find an example:
Example bar chart
In a bar chart the bars do not necessarily have to be separated!
(This is contrary to what some of the books of Numbers & Space say)

What is a histogram?

A histogram is a special name for a bar chart that is made for a table with percentages in it. In a histogram the bars are not separated. Most mathematics books never use this word.

How do you make a bar chart?

First you need the data to be sorted/ordered.
Maybe you need to make a frequency table first.

Just like with a regular graph you need the same steps on the vertical axis. Never choose your scale in such a way that the ratio between your axes is 1 : 2 or bigger.

Example

A number of pupils is asked what their favorite pet is.
The results are in the table below.

Cats74
Dogs   34
Birds20
Fish15
Other7

Make a bar chart for this data.

Use grid paper and choose a sensible scale. In this example, 10 pupils per grid square is the best scale. If you use two grid squares per pet, your diagram will be 8 cm by 10 cm. Cats will get a bar with a length of 7.4 cm, dogs 3.4 cm, et cetera.

You will get something that looks like the bar chart below.
Bar chart for this example