FSSPM directive

Forms the values of SSPM structures.


Options

PRINT = strings
Printed output required (correlations, wmeans, SSPM); default * i.e. no printing

WEIGHTS = variate or symmetric matrix
Variate of weights for weighted SSP, or symmetric matrix of weights (one row and column for each unit of data); default * i.e. all units with weight one

SEQUENTIAL = scalar
Used for sequential formation of SSPMs; a positive value indicates that formation is not yet complete (see READ directive); default * i.e. not sequential


Parameter

    SSPMs
Structures to be formed


Description

FSSPM forms the values for the component parts of SSPM structures, based on the information supplied when the SSPM directive was used to declare them. You can use an SSPM as input to the regression directive TERMS, or the multivariate directives PCP and CVA. The method used to form the SSPM is based on the updating formula for the means and corresponding corrected sums of squares and cross products (Herraman 1968).

   FSSPM has one parameter which lists the SSPM structures whose values are to be formed. If any of these vectors has a missing value, the corresponding unit is excluded from all the means and all the sums of squares and products. You can also exclude units by setting their weights to zero.

   When you have very many units, you may not be able to store them all at the same time within GenStat. You can then use the SEQUENTIAL option of READ to read the data in conveniently sized blocks, and the SEQUENTIAL option of FSSPM to control the accumulation of the sums of squares and products. The SSPM is updated for each block of data in turn until the end of data is found. The PRINT option has no effect until the last set of values is processed, when READ sets the scalar indicator to a negative value.

 

Options: PRINT, WEIGHTS, SEQUENTIAL.

Parameter: unnamed.


Action with RESTRICT

FSSTM takes account of restrictions on any of the variates or factors forming the terms of the SSPM, or on the weights variate or grouping factor if you have specified them.


Reference

Herraman, C. (1968). Algorithm AS12: Sums of squares and products matrix. Applied Statistics, 17, 289-292.