Cumulative frequency – Intermediate & Higher tier - WJECCumulative frequency tables

Cumulative frequency is a running total of the frequencies. This can be represented on a graph by plotting the upper boundary of the groups.

Example

Look at this table:

To create a cumulative frequency table all we need to do is add the frequencies together as we progress down the column.

You can see that there is a total frequency of 20 as this is the number in the last column. While the cumulative frequency column may be harder to interpret, it allows us to construct an effective graphical representation of the data.

This table shows the scores that were obtained by students in an English class:

This table is very similar to the first table but you may have noticed that the class intervals are not the same. The first and last groups cover 20 possible numbers while the central two groups cover only 10 possible outcomes.