If you want to summarize or analyze only a portion of a data set, you can specify criteria for selecting the observations to be used.
To specify criteria for the subset to be used, choose 'Select observations...' from the Locals pull-down menu on the main window. This will bring up a window where you can enter the selection criteria to be applied. These selection criteria are applied temporarily when you request data summarization or analysis; they are not permanently applied to the current data set.
The variable list and observation count in the lower part of the main window reflect any selection criteria you have specified. If you select 'Edit/Browse' from the File pull-down menu on the main window, or if you select 'Save data set listing' or 'Print data set listing' from the Journal pull-down menu on the main window, only the observations meeting the selection criteria are listed.