Grouped data are presented in frequency distributions to save time and effort in entering each observation individually. Standard Deviation is calculated on either a Population (entire population has been sampled) or Sample (only part of the population was sampled).
Given a set of data points ( X1, X2, X3, X4, . . .Xn ) with respective frequencies ( Y1, Y2, Y3, Y4, . . . Yn ), the following programs will calculate Weighted Mean, Population Standard Deviation, and Sample Standard Deviation. This data must be stored in the object 'SIGMADAT' as a 2 x n matrix. (E.g. [ [ X1 Y1 ] [ X2 Y2 ] . . . [Xn Yn ] ] ).