Terminology
Variables are referred to according to the following
conventions:
 factor variables

independent variables used in constructing
the quadratic response surface.
To estimate the necessary parameters, each variable
must have at least three distinct values in the data.
Independent variables must be numeric.
 response variables

the dependent variables to which the
quadratic response surface is fit.
Dependent variables must be numeric.
 covariates

additional independent variables for use in the regression
but not in the formation of the quadratic response surface.
Covariates must be numeric.
 WEIGHT variable
 a variable for weighting the observations in the regression.
The WEIGHT variable must be numeric.
 ID variables
 variables not in the above lists that are transferred
to an output data set containing statistics
for each observation in the input data set.
This data set is created using the OUT=
option in the PROC RSREG statement.
ID variables can be either character or numeric.
 BY variables
 variables for grouping observations.
Separate analyses are obtained for each BY group.
BY variables can be either character or numeric.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.