1. Mean Absolute Deviation

2. DO NOW: Find the mean
The table below shows the findings of eight students and the amount of shoes they own.
Independently, find the mean.
Discuss your findings with your tablemates
Number of shoes owned 12 24 18 17 22 19 20 26

3. Number of shoes owned 158 12 + 20 + 18 + 17 + 22 + 19 + 24 + 26 = 8 8
12 +
20 +
18 +
17 +
22 +
19 +
24 +
26 = 8 8
THE AVERAGE AMOUNT OF SHOES OWNED BY 8 SIXTH
GRADERS IS 19.75

4. MEAN ABSOLUTE DEVIATION
The mean absolute deviation describes variability in the data. Specifically, it is the average distance from each data value and the mean.
Discuss this with your partner put it in your own words.

5. Finding the MAD

6. Visual Representation
MEAN X X X X X X X X 13 15 17 19 21

7. We found the amount of average shoes owned to be 1912 24 18 17 22 19 20 26

8. MEAN X X X X X X X X 13 15 17 19 21
25 26
19 – 12 = 7
| | = 1
19 – = 2
| | = 3
= 1
| | = 5
= 0
| | = 7

9. The mean absolute deviation of this data set is 3.2526
7 +
2 +
1 +
0 +
3 +
7 = 8 8
The mean absolute deviation of this data set is 3.25
Since our mean absolute deviation is a smaller number, we can assume that our data is consistent (or closer together in value). The closer the mean absolute deviation is to 0, the more consistent the data is.

10. Your turn….

11. Did you find…. Speeds of Top Ten Fastest Birds (mph)
Mean of data = mph
Distances from the data = 9.4, 1.6, 13.6, 8.6, 27.4, 13.6, 6.6, 16.4, 1.4, 10.6
Mean of distances = mph
Describe what it represents = Data has variability or it is inconsistent. Large spread

12. In closing….
1. Explain in words the steps to find the mean absolute deviation of a data set.
2. How does the mean absolute deviation describe a data set?
3. Find the mean absolute deviation of this data set and tell how it describes the data