When might you use the OUTPUT statement in a DATA step?

The OUTPUT statement is primarily used within a DATA step to write observations to a dataset. It allows for control over which observations are written and can be particularly useful when creating subsets based on specific conditions. By using the OUTPUT statement strategically, a programmer can selectively output records that meet particular criteria, thus allowing for customized dataset creation tailored to analysis needs.

When you create a subset of data, you may have conditions that determine whether or not certain observations should be included. By employing the OUTPUT statement in conjunction with conditional logic (like IF-THEN statements), you can effectively manage the observations that are written to the new dataset. This makes it a valuable tool for data manipulation and preparation prior to further analysis.

In contrast, the other options involve different functionalities that do not align with the purpose of the OUTPUT statement. For instance, filtering out duplicates is typically done using the SORT procedure with the NODUPKEY option rather than through the OUTPUT statement. Merging datasets usually utilizes the MERGE statement in conjunction with a BY statement, while defining label formats is done via the FORMAT statement. Each of these tasks is handled in a manner distinct from the specific intentions behind using the OUTPUT statement in a DATA step.