All the examples below are based on the ages of children in two playgroups.

In playgroup "A", there are six children with the following ages:

{3, 5, 6, 6, 2, 4 }

In playgroup "B", there are nine children with the following ages:

{4, 3, 5, 6, 3, 6, 3, 2, 4 }

The mean (more correctly called arithmetic mean) is what most people mean when they say "average" in day to day use - usually summarised as "add up all the numbers, then divide by how many of them there are".

The median is the value with half of the numbers above it and half below - or, put another way, the point half way through the list if you arrange it in order of size.

2,3,4|5,6,6

The middle point is between two numbers, 5 and 6, so the median is half way between those two numbers - at 5.5

The median age in Playgroup "A" is 5.5 years.

On the other hand, if we do the same with the ages in playgroup "B":

2,3,3,3,4,4,5,6,6 

This time, the middle is right on a number - not between two of them. That middle number is the median - the median age in Playgroup "B" is 4 years.

The word mode means "fashion". Which value do most of the numbers in the list take? That most common (or most fashionable) value is the mode of the group.

 2, 3,4,5,6,6

The mode of the ages in playgroup "B" is:

 2,3,3,3,4,4, 5, 6,6 

Most recently updated at 06:39 (British time) on 28 September 2006