Comparing distributions

We already know that the mean number of tracks on Kieran's CDs is 11. Deepa also found that the mean number of tracks on her CDs is 11. She therefore came to the conclusion that her results were very similar to Kieran's. Is she correct?

• Here are Kieran's results:
• 10  14  10  12  10  11  12  10  11  9  12

• Here are Deepa's results:
• 2  20  3  17  20  4  5  19  18  2

Although the mean was identical to the mean calculated from Kieran's results, the data is very different. The number of tracks on Deepa's CDs is either very large or very small. Therefore, the range for Deepa's results is also large. From 2 to 20 = 18

Much more information can be gained by giving a measure of central tendency (an average) and a measure of spread (eg, the range).

Now try a Test Bite