Variance and Standard Deviation
Skill
 Type
 Description
 Source

Variance and Standard Deviation 
Worksheet 
In this leaflet we introduce variance and standard deviation as measures of spread. We can evaluate the variance of a set of data from the mean, that is how far the observations deviate from the mean. 
MathCentre 
Variance and Standard Deviation  Grouped 
Worksheet 
In this leaflet we extend the definitions of variance and standard deviation to data which has been grouped. 
MathCentre 
Measures of Spread 
Worksheet 
On completion of this worksheet you should understand what is meant by a measure of spread and be able to calculate range, interquartile range and standard deviation 
Coventry University 
Variance of a Population 
Video  12:23 mins 
The video introduces how to calculate the variance for a population by hand. 
Khan Academy 
Sample Variance 
Video  11:17 mins 
The video introduces what the difference is between the population and the sample variances, and how to calculate the variance for a sample by hand. 
Khan Academy 
Standard Deviation 
Video  13:06 mins 
The video summaries what the difference is between the main estimators for a population and for a sample, and how to calculate the standard deviation by hand. 
Khan Academy 
Alternate Variance Formulas 
Video  12:17 mins 
The video introduces other formulas to calculate the variance which may simplify your calculations. 
Khan Academy 
Variance of Differences of Two Random Variables 
Video  10:46 mins 
The video introduces how to calculate the variance of the differences of two continuous random variables. This may be needed for a twosample paired t test. 
Khan Academy 

Enquries, feedback and comments to: Chetna.Patel@shef.ac.uk
