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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