Child Development 133 
Research Methods in Human Development

Sections 01 & 05
Hembree            Fall, 2012

 

How to Compute Variance (s2) and Standard Deviation

 

To compute Variance (s2):

  s2= Σ(X-X)2
           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

 

 

X

X-X

(X-X)2

 

       
     

 

     

 

     

 

     

 

 

 

Σ =

s2= Σ(X-X)2
     N-1

 

 

 

 

 

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

California State University, Sacramento
College of Education
Department of Child Development

Updated: August, 2012