PLS PROCEDURE OPTIONS

The data for PLS are supplied using the X and Y parameters, as pointers to 
variates containing the columns of the X and Y matrices. Other parameters
allow output to be saved in appropriate data structures.

'options'
PRINT      = strings  Printed output required (data, xloadings,
                      yloadings, ploadings, scores, leverage,
                      xerrors, yerrors, scree, xpercent, ypercent, 
                      predictions, groups, estimates, fittedvalues); 
                      default esti,xper,yper,scor,xloa,yloa,ploa
NROOTS     = scalar   Number of PLS dimensions to be extracted
YSCALING   = string   Whether to scale the Y variates to unit variance;
                      (yes, no); default no
XSCALING   = string   Whether to scale the X variates to unit variance;
                      (yes, no); default no
NGROUPS    = scalar   Number of cross-validation groups into which to divide 
                      the data; default 1 (i.e. no cross-validation performed)
SEED       = scalar   A scalar indicating the seed value to use when 
               or     dividing the data randomly into NGROUPS groups for the 
             factor   cross-validation or a factor to indicate a specific set
                      of groupings to use for the cross-validation; default 
                      takes the (scalar) value of NGROUPS
LABELS     = text     Sample labels for X and Y that are to be used in the
                      printed output; defaults to the integers 1...n where
                      n is the length of the variates in X and Y
PLABELS    = text     Sample labels for XPREDICT that are to be used in
                      the printed output; default uses the integers 1, 2 ...

'parameters'
Y          = pointers Pointer to variates containing the dependent variables
X          = pointers Pointer to variates containing the independent variables
YLOADINGS  = pointers Pointer to variates used to store the Y component
                      loadings for each dimension extracted
XLOADINGS  = pointers Pointer to variates used to store the X component
                      loadings for each dimension extracted
PLOADINGS  = pointers Pointer to variates used to store the loadings for
                      the bilinear model for the X block
YSCORE     = pointers Pointer to variates used to store the Y component
                      scores for each dimension extracted
XSCORE     = pointers Pointer to variates used to store the X component
                      scores for each dimension extracted
B          = matrices A diagonal matrix containing the regression
                      coefficients of YSCORE on XSCORE for each dimension
YPREDICT   = pointers A pointer to variates used to store predicted Y values
                      for samples in the prediction set
XPREDICT   = pointers A pointer to variates containing data for the
                      independent variables in the prediction set
ESTIMATES  = matrices An NX+1 by NY matrix (where NX and NY are the numbers
                      of variates contained in X and Y respectively) used to
                      store the PLS regression coefficients for a PLS model
                      with NROOTS dimensions
FITTED     = pointers Pointer to variates used to store the fitted values for
                      each Y variate
LEVERAGE   = variates Variate used to store the leverage that each sample has
                      on the PLS model
PRESS      = variates Variate used to contain the Predictive Residual Error
                      Sum of Squares for each dimension in the PLS model, 
                      available only if cross-validation has been selected
RSS        = variates Variate used to store the Residual Sum of Squares for
                      each dimension extracted
YRESIDUAL  = pointers Pointer to variates used to store the residuals from the
                      Y block after NROOTS dimensions have been extracted,
                      uncorrected for any scaling applied using YSCALING
XRESIDUAL  = pointers Pointer to variates used to store the residuals from the
                      X block after NROOTS dimensions have been extracted,
                      uncorrected for any scaling applied using XSCALING
XPRESIDUAL = pointers Pointer to variates used to store the residuals from the
                      XPREDICT block after NROOTS dimensions have been
                      extracted

It is usual to centre all variables prior to a PLS analysis, the procedure 
will automatically do so even if the XSCALING/YSCALING options are not set. 
On exit from the procedure the variates pointed to by X and Y are unchanged.

Partial Least Squares Regression 27.2.96 Page : 15d of 16