Unlike the GLM procedure, only main effect
terms are allowed in the model specification.
For numeric variables, this is a linear term equal to the value of
the variable unless the variable appears in the CLASS statement.
For variables listed in the CLASS statement, PROC LIFEREG
creates indicator variables (variables taking the values zero
or one) for every level of the variable except the last level.
If there is no intercept term, the first class
variable has indicator variables created
for all levels including the last level.
The levels are ordered according to the ORDER= option.
Estimates of a main effect depend upon other
effects in the model and, therefore, are adjusted
for the presence of other effects in the model.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.