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The Standard Deviation :: Standard Deviation Calculation
Calculate the Standard Deviation for the following data using the calculator to the right (round to 1 decimal points). Click on the Check Answer button to see how you did.
Data:
3, 5, 11, 17, 18, 19, 20
1
Add up all the values.
Sum
93
2
Count the total number of values.
n
7
3
Divide the Sum by the the total number of values.
Mean
13.3
4
Subtract the mean from each value. Then Square that result.
Value
Value-Mean
(Value-Mean)
2
3
-10.3
106.1
5
-8.3
68.9
11
-2.3
5.3
17
3.7
13.7
18
4.7
22.1
19
5.7
32.5
20
6.7
44.9
5
Add up all the squared deviations.
Sum of Squared Deviations
293.5
6
Divide the Sum of Squared Deviations by n-1.
Sample Variance
48.9
7
Take the square root of the variance.
sample standard deviation
7
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April 17, 2010 | Marie wrote:
sample variance did not make sense. Divide the sum of squared deviations n-1
September 21, 2009 | anonomous wrote:
This was an excellent tutorial on stsndard deviation. Thank Y
September 15, 2009 | Dave Mills wrote:
Excellent course! Thnak you!
March 18, 2009 | Omar wrote:
Why do you divide the Sum of Squared Deviations by n-1 to get the sample variance?
