You can specify a BY statement with PROC PHREG to obtain separate
analyses on observations in groups defined by the BY variables.
When a BY statement appears, the procedure expects the
input data set to be sorted in order of the BY variables.
The variables are one or more variables in the input data
- BY variables ;
If your input data set is not sorted in ascending order, use
one of the following alternatives:
- Sort the data using the SORT procedure with a similar BY statement.
- Specify the BY statement option NOTSORTED or DESCENDING
in the BY statement for the PHREG procedure.
The NOTSORTED option does not
mean that the data are unsorted but rather that
the data are arranged in groups (according to values
of the BY variables) and that these groups are not
necessarily in alphabetical or increasing numeric order.
- Create an index on the BY variables using the DATASETS procedure
(in base SAS software).
For more information on the BY statement, refer to the discussion
in SAS Language Reference: Contents.
For more information on the DATASETS procedure, refer to the
discussion in the SAS Procedures Guide.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.