What is the primary purpose of a DATA step in SAS programming?

The primary purpose of a DATA step in SAS programming is to read in a data file. This step is fundamental because it allows SAS to access and manipulate datasets, regardless of whether they reside in an external file, a database, or are being generated from another data source. The DATA step facilitates the entry, transformation, and preparation of data for analysis.

With the DATA step, users can specify the structure of the data set, apply various transformations or calculations, and create new variables. While it can also be used to perform actions that prepare data for statistical analysis or reporting later in the process, the initial and crucial function of the DATA step is to import or generate datasets for further use in analysis, making reading in data the focal point of its purpose.

In contrast, the other options focus on activities typically associated with different procedural steps or features in SAS. Statistical analysis and generating graphical reports fall under the capabilities of PROC steps or dedicated procedures in SAS, while executing SQL queries pertains to using the SQL procedure, which is distinct from the function of the DATA step.