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The Standard Deviation
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Standard Deviation Calculation Short-Cut Method
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This method might be a bit faster to calculate. 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:
6, 7, 9, 12, 17, 18, 20
1
Add up all the values.
Sum
89
2
Square this sum
Sum Squared
7921
3
Count the total number of values.
n
7
4
Divide Sum Squared by the the total number of values
Avg. Sum Squared
1131.57
5
Square each individual value.
6
6
2
36
7
7
2
49
8
9
2
81
9
12
2
144
10
17
2
289
11
18
2
324
12
20
2
400
13
Add up all these squared values.
Sum of Squares
1323
14
Subtract Sum of Squares - Avg. Sum Squared
191.43
15
Divide this by the total number of values minus 1.
sample variance
31.91
16
Take the square root of the variance.
sample standard deviation
5.65
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May 28, 2009 | brandee dungan wrote:
i do not understand where or how to get sample variance value. everything else makes since.
