Macro returning a value

Question

I created the following macro. Proc power returns table pw_cout containing column Power. The data _null_ step assigns the val

Answer 1

You can't do what you're trying to do this way. Macros in SAS are a little different than in a typical programming language: they aren't subroutines that you can call, but rather just code that generate other SAS code that gets executed. Since you can't run proc power inside of a data step, you can't run this macro from a data step either. (Just imagine copying all the code inside the macro into the data step -- it wouldn't work. That's what a macro in SAS does.)

One way to do what you want would be to read each observation from tmp one at a time, and then run proc power. I would do something like this:

/* First count the observations */
data _null_;
  call symputx('nobs',obs);
  stop;
  set tmp nobs=obs;
run;

/* Now read them one at a time in a macro and call proc power */
%macro power;
  %do j=1 %to &nobs;
    data _null_;
       nrec = &j;
       set tmp point=nrec;
       call symputx('meanA',meanA);
       call symputx('stdA',stdA);
       call symputx('nA',nA);
       call symputx('meanB',meanB);
       call symputx('stdB',stdB);
       call symputx('nB',nB);
       stop;
    run;

   proc power; 
     twosamplemeans test=diff_satt 
     groupmeans = &meanA | &meanB 
     groupstddevs = &stdA | &stdB
     groupns = (&nA &nB)
     power = .;    
    ods output Output=pw_out;
  run;

  proc append base=pw_out_all data=pw_out; run;
 %end;
%mend;

%power;

By using proc append you can store the results of each round of output.

I haven't checked this code so it might have a bug, but this approach will work.