The SSM Procedure

Programming Statements

To define the model, you can use most of the programming statements that are allowed in the SAS DATA step. See the SAS Language Reference: Dictionary for more information. For the most part, the syntax of programming statements used in PROC SSM is identical to that used in the MODEL procedure (see ChapterĀ 19: The MODEL Procedure) and the NLMIXED procedure (see ChapterĀ 70: The NLMIXED Procedure in SAS/STAT 13.2 User's Guide). However, there are some restrictions: the DATA step lagging and differencing functions are not allowed, and the use of character variables in the DATA step expressions is not permitted. These are not serious restrictions; usually you can overcome them by adding the variables that are created by such operations to the input data set before its use in the SSM procedure.