Child Development 133 (03, 04,
72, 73 & 74)
Research Methods in Human Development

Hembree            Spring, 2013

 

How to Compute Variance (s2) and Standard Deviation

 

To compute Variance (s2):

 

 

X

X-X

(X-X)2

 

       
     

 

     

 

     

 

     

 

 

 

SS(sum of squares)

 

s2= SS
     N-1

 

 

S2=    SS    =   Σ(X-X)2
           N-1          N-1

1) Compute mean of the numbers

2)  Subtract mean from each number (deviation from the mean)

3)  Square the deviations from the mean

4)  Sum the squared deviations and divide by N -1 to obtain the variance (s2)

5)  The standard deviation (s) is square root of the variance.

 

Send problems, comments or suggestions to: hembrees@csus.edu

California State University, Sacramento

College of Education

Department of Child Development

Updated: January 25, 2013

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