VoseVariance

See also: VoseMoments

VoseVariance(Distribution Object)

 

 

Example model

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.

 

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