1. Data Handling Mean, Median, Mode All three are used as a way of saying average

2. Data Handling Mean This is what normally think of as average. Take this set of 10 numbers: 22, 26, 18, 26, 28, 25, 15, 26, 17, 24 When we add them up and divide by 10… = 22.7 Why divide by 10?

3. Data Handling Median The median is the number which is in the middle when they are placed in rank order 22, 26, 18, 26, 28, 25, 15, 26, 17, 24 15171822242526 28 The median number is the middle value In this example it is 24.5

4. Data Handling Mode The Mode is the number that appears most often (easy to see when ranked). 22, 26, 18, 26, 28, 25, 15, 26, 17, 24 15171822242526 28 26 appears more often than any other number.

5. Data Handling Range The Range is the difference between the smallest and largest number: 15171822242526 28 28 – 15 = 13

6. Data Handling What is Average? This set of numbers has produced 3 averages Mean = 22.7, Median = 24.5, Mode = 26 Which one should we choose? 15171822242526 28 This is the whole point of using data. We can choose the one that helps us to make a point best!

7. Data Handling The average number of accidents in a workplace a month is only 22.7 15171822242526 28 But look at all of the months where there were more than 22 accidents!!

8. Data Handling The average earning is £24.50 per day! 15171822242526 28 But look at how low some earnings are! There is a £9.50 gap between £15 and £24.50 but only £3 between £24.50 and £28!

9. Data Handling The average contents in each packet is 26 15171822242526 28 Based on the mode this is true… but look at how few some packets contain!

10. Data Handling In a maths test you will have to be able to explain WHY it might be unfair to use one average rather than another. You will also be required to explain why a survey which has been designed might produce poor quality or biased information, for example, a car survey carried out on a busy road counting vehicles between 10:00am and 11:00am. Discuss!