st: local macro vs. database variable

[Cade Massey <cade.massey@duke.edu>]

Can anyone tell me why the following two sub-routines would generate 
different results?  This code is buried in the middle of a long 
estimation program.  I'm trying to get away with imposing on you as 
little of the program as possible -- not sure if this will be enough to 
tell.  "trial2" is a variable in the dataset.

Original approach:
.gen double `dum1'=$A1*(k1+k2+k3+k4)+$C1*trial2

Modified approach:
.local trial=trial2
.gen double `dum1'=$A1*(k1+k2+k3+k4)+$C1*`trial'

The original approach works fine, but I need to modify it as I write a 
new program.  In case it is of any help, I have one additional clue: the 
residual SS is the same for both programs on Iteration 0, but grows 
steadily apart after that.  The modified approach provides a poorer fit 
and requires more iterations to converge.

I'd guess that I'm doing tomething wrong by substituting a local macro 
for a variable, but I seem to need that variable in a macro.  Or maybe I 
don't.  Leads me to a highly related question: If I have 20 local macros 
defined as `parm1' - `parm20', where the suffix indexes a "trial" 
variable in the dataset, what is the best way to call those macros in my 
program?  If trial is a local macro, I can use:

gen double `dum1'=`parm`trial''.

But with "trial" as a variable, I haven't been able to find a syntax 
that works.  So I need to learn either 1) how to use a variable value as 
a suffix in a local macro name, or 2) how to create a local macro that 
stands in for a variable.

Thanks.
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