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Download a pdf copy of this help file here |
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Download a pdf copy of this help file here |
See also: VoseMoments
VoseVariance(Distribution Object)
Returns the variance of a distribution. If a closed formula for the variance exists, this is used.
For example, VoseVariance(VoseNormalObject(10,2))
will return the value 4 because the variance of a normal
distribution is equal to its second parameter 
squared.
Note that for each available distribution we have included a Distribution equations topic with the formulas for the mean, variance, skewness and kurtosis (if they exist): see for example Normal equations.
The variance is a measure of how much the probability distribution is spread from the mean:
where 
denotes
the expected value (mean)
of whatever is in the brackets, so:
The variance sums up the squared distance from the mean of all possible values of x, weighted by the probability of x occurring. The variance is known as the second moment about the mean. It has units that are the square of the units of x. So, if x is cows in a random field, V has units of cows2. This limits the intuitive value of the variance. To calculate standard deviation we use the VoseStDev function.
Example model