The X13 ProcedureOverviewGetting StartedSyntaxDetailsExamplesReferencesBY Statement BY variables; A BY statement can be used with PROC X13 to obtain separate analyses on observations in groups defined by the BY variables. When a BY statement appears, the procedure expects the input DATA= data set to be sorted in order of the BY variables. Copyright © SAS Institute Inc. All rights reserved.Last updated: August 11, 2020