10.2 Using Statistics

Now you can work out several different statistical measures.
In a real situation, you need to decide which one to use.

If you want to measure how to spread out a set of measurements is, the range is the most statistic.

If you want to find a representative measurements, you need an average. Should it be the mode, median or the mean? That depends on the particular situation.

Here is a summary to help you decide which average to choose.

• Choose the Mode if you want to know which is the most commonly occuring number.
• The Median is the middle value, when the data values are put in order. Half the number are greater than the median and half the numbers are less than the median.
• The Mean depends on every value. If you change one number you change the mean.

WORKED EXAMPLE:

Here are the ages, in years, of the players in a football team. Work out the average age. Give a reasonfor your chioce of average.

16

17

18

18

19

20

20

21

21

32

41

• The mode id not a good choice

            There are three modes. Each has a frecuency of only 2

• The mean will be affected by the two oldest people

             They are much older and will dostort the value. In fact, the mean is 22.1 and nine people are      younger than this; only two are older

• The median is 20 and this is the best average to use in this case

            Five players are younger than the median and five are older