ORTHOREG Procedure
The ORTHOREG procedure fits general linear models by the method of least squares. Other SAS/STAT software procedures, such
as the GLM and REG procedures, fit the same types of models, but PROC ORTHOREG can produce more accurate estimates than other
regression procedures when your data are illconditioned. The following are highlights of the ORTHOREG procedure's features:
 uses GentlemanGivens transformations to update and compute the upper triangular matrix R of the QR decomposition of the data matrix
 enables you to construct special collections of columns for design matrices
 produces a display of the fitted model and provides options for changing and enhancing the displays
 enables you to perform F tests for model effects that test Type I, Type II, or Type III hypotheses
 enables you to obtain custom hypothesis tests
 computes and compares least squares means (LSmeans) of fixed effects

 provides a general mechanism for performing a partitioned analysis of the LSmeans for an interaction
 enables you to save the context and results of the statistical analysis in an item store, which can be processed by the PLM procedure
 performs weighted estimation
 performs BY group processing, which enables you to obtain separate analyses on grouped observations
 creates SAS data sets for analysis of variance, fit statistics, table of class variables, and parameter estimates

For further details see the SAS/STAT User's Guide:
The ORTHOREG Procedure
( PDF  HTML )
Examples