Local macros are a very useful feature of Stata. Here is a simple example.
local macro1 “Hello!”
local macro2 = “How are you?”
local macro3 2+2
local macro4 = 2+2
di ” `macro1'`macro2′ ”
di “Here’s some math: `macro3' = `macro4′ ”
A few comments are in order here. macro1′ tells Stata to replace this expression with the contents of the local macro1. Make sure to leave no spaces inside the `’. Also, note how macro3 and macro4 lead to different outcomes. You need to use the equal sign to make Stata to evaluate the expression, otherwise it will treat it like a string.
Now, Stata applies the “parentheses rule” when replacing local macros for their contents. That is, it first replaces the innermost local macro, then the second innermost local macro, and so on. Here is an example.
local macro5 “nest”
local nestmacro “Local macros can be nested!”
di ” “macro5’macro’ ”
Let’s add another layer to the nesting of the previous example and play with it a little bit more:
local macro5 “nest”
local macro6 “macro”
local macro7 5
local nestmacro “Local macros can be nested!”
di ” “macro`macro7”`macro6” ”
I guess you have a pretty good idea of how this works now. Good luck in your Stata coding.