SAS macro variables are part of the macro facility, which is a tool for extending and customizing SAS software and for reducing the amount of text you must enter to complete tasks. A macro variable is independent of a SAS data set and contains one value that remains constant until you change it. The value of a macro variable is a text string that becomes part of your program whenever the macro variable is referenced.

You can assign any text string to a macro variable. For example, three possible values are shown below:

Region Five Tests
1999
SITE8.TRIALS

The assigned text is then placed into your program whenever the macro variable is referenced.

                      [Macro Variable]
                           1 9 9 9
                          . .   . .
                         .  .   .  .
                        .   .   .   .
                       .    .   .    .
     title "Temporary Employees for 1999";
                    .       .   .
     data hrd.temp1999;     .   .
        set hrd.temp;       .   .
        if YEAR(enddate)=1999;  .
     run;                       .
     proc print data=hrd.temp1999;
     run;

Macro variables can be defined and referenced anywhere in a SAS program except within data lines. So, if your DATA step reads instream data, which is data included in the program, you cannot define or reference a macro variable within these lines.

     data site6.trial;
        input name $ sex $ age level1 level2;
        datalines;
     Treborn F 35 254 309
     Washington M 27 198 167
     Randell M 43 155 150
     Farley F 60 202 210
     ;
     run;
     proc print data=site6.trial;
     run;

Types of Macro Variables

There are two types of macro variables:

• automatic macro variables
• user-defined macro variables.

As these names suggest, automatic macro variables are provided by SAS software, whereas you create and define the value of user-defined macro variables.

You learn more about each type of macro variable in the next two sections of this lesson.