Unit 4: CALCULATING Mean Absolute DEVIATION Notes
The standard deviation is used to tell how far on average any data point is from the mean. The
smaller the standard deviation, he closer the scores are on average to the mean. When the
standard deviation is large, the scores are more widely spread on average from the mean.
The standard deviation is calculated as the average distance from the mean. It is also
referred to as the Mean Absolute Deviation (MAD)
Example Problem:
The junior high basketball team played ten games. Find the standard deviation for the number
of baskets scored by the team in the 1st half for the ten games:
0, 4, 5, 6, 6, 7, 7, 8, 8, 9
Follow the steps below to calculate the MAD.
Step 1: Find the mean of the data set.
Step 2: Write down each score in the Data Item column of the table below.
Step 3: Subtract each of the scores from the mean. Record the difference in the Deviation
From The Mean column in the table below.
Step 4: Find the Absolute value of each deviation from mean. Record the answers in the 3rd
column
Step 5: Add the absolute values from column 3 and then divide by the number of items in the
data set to get the MAD.
0+4+5+6+6+7+7+8+8+9 = 60 ÷ 10 Mean = 6
Data Item
0
4
5
6
6
7
7
8
8
9
Deviation from
Mean
0-6= -6
4-6= -2
5-6 = -1
6-6= 0
6-6 = 0
7-6 = 1
7-6 = 1
8-6= 2
8-6= 2
9-6= 3
Total
Absolute Value of
Deviation from Mean
ǀ-6 ǀ = 6
÷ 10 =MAD
MAD =
Using the data sets below, follow the steps, create a table and find the mean average
deviation for each. Make a Table!
Try It! #1- 33, 25, 42, 25, 31, 37,46,29, 38
Try It! #2 - 20, 15, 23, 8, 20, 10, 15, 25, 16, 18