Mode

The mode

The mode is the number which occurs most often in a set of data. There can be more than one mode.

Have another look at Kieran's results and find the mode:

9 13 9 11 9 13 11 9 10 8 11

We need to identify the number that appears in this set of numbers the most. Sometimes it helps to list the numbers in numerical order:

8 9 9 9 9 10 11 11 11 13 13

Here we can see that the number 9 occurs most often, so 9 is the mode.

From a frequency table, it is even easier to spot the mode.

 

Number of tracks on CD	Number of CDs
8	1
9	4
10	1
11	3
12	0
13	2

There are four CDs with 9 tracks. The other numbers of tracks do not occur four times or more, so 9 is the mode.

Group data and modal classes

When we have a lot of categories, we sometimes need to group the data.

This table shows the shoe sizes of 100 people in a shop:

 

Shoe size	Number of people
10-19	6
20-29	8
30-39	35
40-49	51

The groups 10-19, 20-29, 30-39 and 40-49 are called classes.

The class with the most people is 40-49. We therefore call this the modal class.