Åk 6–9

4.2 Frequency Diagram
A bar chart is used when the statistical material can only have certain values, for example numbers.  Normally the numbers represent a number of something (observations).

A survey was done in a class about how many siblings each student had.
There were 23 students in the class.

The results were written up in a frequency table.  The observations in this case are the number of siblings.The frequency indicates how many students have a certain number of siblings. For example, there were four students who had three siblings.

Frequency Table

Then a diagram is drawn.  It is important here to remember to use a straight edge and be careful that every mark has the same distance between them.

In a bar chart, there are two axis; the x- and y-axis.

On the y-axis, the vertical one, the frequency is normally given.  In other words, how often something occurs.  On the x-axis, the horizontal one, observations are recorded.