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

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

















Σ =

s2= Σ(X-X)2






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

Updated: August, 2012