st: using different macros everytime

[Shehzad Ali <sia500@york.ac.uk>]

Hi,

This is probably a very simple question but just reflects my inexperience 
of using foreach loops.

I want to run a 2 separate treatreg models with the same y var but 
different set of x vars. Here is what I am doing:

* First model:

local xvar "x1 x2"  
local zvar "x1 x2 v1"

treatreg y1 $xvars, treat(y2=$zvars)

* Second model:

local xvar "x1 x2 x3"  
local zvar "x1 x2 x3 v1"

treatreg y1 $xvars, treat(y2=$zvars)

Now I want to loop this somehow so that I just write the - treatreg - line 
once but - foreach - can pick up different sets of macros. Can you suggest 
the best way to do it?

Thank you,

Shehzad
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