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The Standard Deviation :: Standard Deviation Calculation Short-Cut Method
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:
1, 3, 5, 7, 10, 14, 19
1
Add up all the values.
Sum
59
2
Square this sum
Sum Squared
3481
3
Count the total number of values.
n
7
4
Divide Sum Squared by the the total number of values
Avg. Sum Squared
497.29
5
Square each individual value.
6
1
2
1
7
3
2
9
8
5
2
25
9
7
2
49
10
10
2
100
11
14
2
196
12
19
2
361
13
Add up all these squared values.
Sum of Squares
741
14
Subtract Sum of Squares - Avg. Sum Squared
243.71
15
Divide this by the total number of values minus 1.
sample variance
40.62
16
Take the square root of the variance.
sample standard deviation
6.37
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November 15, 2011 | sakura wrote:
how is this a shortcut? i already know how to use a calculator. the point of a shortcut was to find a way to get the standard deviation without having to go through the pain of having to square each individual value every single time! when you're working with 30+ numbers this is unbelievably irritating, calculator or no. this isn't a shortcut!
May 28, 2009 | brandee dungan wrote:
i do not understand where or how to get sample variance value. everything else makes since.
