Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and chemometrics......click here for more. 
Home Univariate Data Measures of Variation Variance  
See also: precision of results, fractile, variability, standard deviation, mean, Exercise  Measure your reaction time  
VarianceIn addition to the measures of location for describing the position of the distribution of a variable, one has to know the spread of the distribution (and, of course, about its form). Maybe you want to have a look at the following interactive example in order to see some examples of common means but different spreads. The spread of a distribution may be described using various parameters, of which variance is the most common one. Mathematically speaking, the variance v is the sum of the squared deviations from the mean divided by the number of samples less 1: Examination of this formula should lead to at least three questions:
The variance of some data is closely related to the precision
of a measuring process, as can be seen in the following interactive example .


Home Univariate Data Measures of Variation Variance 