Comparing data

We know that the mean number of tracks on Kieran's albums is 11. Deepa also counted the number of tracks on her albums and calculated the mean to be 11 as well.

Here are Deepa's results:

2, 20, 3, 17, 20, 4, 3, 16, 4 , 5, 19, 18 and 12

She therefore came to the conclusion that her results were very similar to Kieran's. But this is not the case.

Here are Kieran's results:

10, 14, 10, 12, 11, 10, 11, 12, 10, 11, 9 and 12.

His range is 5.

Although Deepa's mean is the same as Kieran's mean the results are very different. Some results are a higher or lower.

The number of tracks on Deepa's albums goes from 2 to 20.

Range = 20 - 2 = 18

More information can therefore be shown by giving a measure of spread as well as an average.