Calculates the sample variance for the grouped data which has been set using SetMidpoints or SetFrequencies.
Remark: Variance of the grouped data set is an approximation of the variance of the underlying data set. The reason for this is that the midpoints of the collections of data points set using SetMidpoints, are an approximation of the values of the points within that subinterval.
GroupedData Class | WebCab.COM.Statistics.Statistics Namespace