You can specify a BY statement with PROC ORTHOREG 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.
- BY variables ;
If your input data set is not sorted in ascending order,
use one of the following alternatives:
For more information on the BY statement, refer to the discussion
in SAS Language Reference: Concepts.
For more information on the DATASETS procedure, refer to the
discussion in the SAS Procedures Guide.
- Sort the data using the SORT procedure with a similar
- Specify the BY statement option NOTSORTED or DESCENDING
in the BY statement for the ORTHOREG 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).
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