How to set a macro variable that has '+' and is used in the proc model step?

[xizidememeda]

Hi guys! Could you please give me some help for my urgent question on setting a macro variable? I will appreciate it very much for your warm help!

I need to set a macro variable 'indep = a + b1* mkt + b2 * smb + b3 * hml' and use it in the following proc model step. However, it doesn't work. How can I set a macro variable which has '+' signs in this situation? Your answer will help me a lot!

proc model data=ret_5; 
	 by  id;
	 parms a b1 b2 b3;
	 instruments mkt smb hml;
	 exret = &indep; 
	 fit exret / gmm kernel=(bart, 2, 0);
	 ods output parameterestimates=cs;
quit;

[Shmuel]

Have you tried to precede proc model by next statement:

%let indep = a + b1* mkt + b2 * smb + b3 * hml;

thus assigning the value to the macro variable.

if positive, then explain what do yo mean by "it doesn't work." ?

In such case better post the log with your explanatin.

[xizidememeda]

Hi! The log informs me to define the variable preceding proc model. But I need to change the 'indep' with other variables in this macro each time. If I use the %let statement in the macro, it seems I have to change this variable in the macro. Can I just change it each time with other macro variables together when calling this macro? Many thanks for your help! 

[Shmuel]

Would you prefer the code:

%let test =  a + b1* mkt + b2 * smb + b3 * hml;
proc model data=ret_5; 
	 by  id;
	 parms a b1 b2 b3;
	 instruments mkt smb hml;
	 exret = indep = &test;    /* any time replace the indep into wanted variable */ 
	 fit exret / gmm kernel=(bart, 2, 0);
	 ods output parameterestimates=cs;
quit;

[xizidememeda]

Hi~Thanks for your reply! But it seems I still need to change the test variable each time in the macro, right?

[Shmuel · Accepted solution]

Alternatively you may prefer next code:

%let formula =  a + b1* mkt + b2 * smb + b3 * hml;

%macro p_model(var,tst,dsn=ret_5);
proc model data=&dsn; 
	 by  id;
	 parms a b1 b2 b3;
	 instruments mkt smb hml;
	 exret = &var = &tst ;   
	 fit exret / gmm kernel=(bart, 2, 0);
	 ods output parameterestimates=cs;
quit;
%mend p_model;

%p_model(indep,&formula);  /* input = ret_5 the default dataset */

%p_model(anyvar,&formula );  

%p_model(new_var, <new_formula>, dsn=<any_dataset>); /* any other input */

[xizidememeda]

Thanks! Could you please give me a little more explanations? I don't understand what the meaning of 'exret = &var = &formula' is. What's more, when using &macro (indep=), it seems I have already define a macro variable indep and I can directly call indep by using %macro (indep= a + b1* mkt + b2 * smb + b3 * hml);, why I need to define the variable again?

[Shmuel]

A short explanation to macro programming:

1) Assigning a value to a macro variable is done by:

%LET <macro_variable_name> = any string;

2) Defining a macro program is done by:

%MACRO <macro_program_name>(arguments seaparated by comma);
       ... sas code to run ...
       ... using &<macro_variable> or &<argument> to be replaced at run time
             by their assigned value 
       .........
%MEND [<macro_program_name>];  /* closes the macro program */

%<macro_program_name>( assigned arguments); /* execute the macro program */

3) There are two kinds of arguments that can be defined with a macro program:

   3.1) positional arguments must be given in same order as defined in the macro program.

   3.2) named arguments must follow after all positional arguments.

          You can assign a default value to named argument only, and

          you can override the default value at invoking the macro program to be executed;

There is much more to learn about macro language .

Welcome to a new sas field.

[xizidememeda]

The log reports: All positional parameter variables in the %MACRO statement must be listed before any keyword parameter variable is listed

[xizidememeda]

Hi! I have revised my code based on your suggestion and it works now! Thanks soooo much!

[ballardw]

Really, you need to show how you build your macro variable INDEP