Declares one or more SSPM data structures.
||Terms for which sums of squares and products are to be calculated; default
||Maximum number of vectors in a term; default 3|
||Full factor parameterization (
||Groups for within-group SSPMs; default
||Number of degrees of freedom for sums of squares; default
||Identifiers of the SSPMs|
||Symmetric matrix to contain the sums of squares and products for each SSPM|
||Variate to contain the means for each SSPM|
||Number of units or sum of weights for each SSPM|
||Pointers to variates of group means for each SSPM|
The SSPM structure stores a matrix of corrected sums of squares and products, and associated information, as used for regression and some multivariate analyses. You can form values for SSPM structures by the
FSSPM directive. However, most multivariate and regression analyses can be done without declaring and forming an SSPM explicitly.
An SSPM comprises four structures (identified by their suffixes). Their labels can be specified in either upper or lower case, or any mixture.
['Sums'] is a symmetric matrix containing the sums of squares and products. The number of rows and columns of this matrix will equal the number of parameters defined by the expanded terms list: that is, the number of variates plus the number of dummy variates generated by the model formula. (See the
['Wmeans'] is a pointer, pointing to variates holding within-group means. There is one variate for each row of the
'Sums' matrix plus one extra. They are all of the same length, namely the number of levels of the
GROUPS factor. The extra variate holds counts of the number of units in each group.
TERMS option of the
SSPM directive defines the model for whose components the sums of squares and products are to be calculated. In the simplest case the model is just a list of variates, but you can use more complex model formulae, involving variates and factors; this is done in conjunction with the
Sometimes you may already have calculated values for the matrix of sums of squares and products. You can then assign them to the component structures of the SSPM for example by
READ. You would still, however, need to set the number of degrees of freedom associated with the matrix, and for that you use the
The parameter lists let you specify identifiers for the four components of an SSPM. You can have declared them previously (and you can have given them values), but if so they must be of the correct type.
" Example SSPM-1: declaring an SSPM structure" READ [SETNVALUES=yes] V[1...5] 1 4 7 1 0 4 2 1 0 1 3 0 1 1 3 : SSPM [TERMS=V[1...5]] Ssp FSSPM [PRINT=sspm] Ssp