What is the primary function of the SYMBOL statement in SAS programming?

The primary function of the SYMBOL statement in SAS programming is to define plotting symbols used in graphical procedures. By utilizing the SYMBOL statement, programmers can customize the appearance of symbols in plots, such as changing their shape, size, and color. This is particularly useful when creating graphs and charts where visual representation is critical for conveying information effectively. Through the SYMBOL statement, you can specify various attributes like line types, fill patterns, and marker designs, allowing for a tailored visual output that matches the analysis being presented.

The other choices reflect different aspects of SAS functionalities but do not pertain to plotting symbols. Data input control is typically managed through data step programming or specific input statements. Output displays can be adjusted by using other statements focused on reporting, such as the PROC PRINT for displaying data in a tabular format. Importing data from external files is done using procedures like PROC IMPORT or the DATA step with infile statements. Each of these functions serves a different purpose within the SAS environment, highlighting the specialized role of the SYMBOL statement in the context of graphical representations.