--- K Jensen wrote:
> I would like to generate lists of groups of variables that have been
> generated via xi from the column names of the vector e(b) after
> regression commands.
> It's probably easier to explain with an example...
>
> sysuse cancer
> stset studytime, fail(died)
> gen randcat=1
> replace randcat=2 if uniform()>1/3
> replace randcat=3 if uniform()>2/3
> xi:stcox i.drug age i.randcat
>
> . matrix list e(b)
>
> e(b)[1,5]
> _Idrug_2 _Idrug_3 age _Irandcat_2 _Irandcat_3
> y1 -1.7300519 -3.2313217 .12791436 -.93457115 -.77850524
>
> I would like to take the column names from e(b) to generate a varlist
> of the xi-generated variable groups, something like:
>_Idrug* _Irand*
With the -unab- command you can get a list of all variable names
starting with _I, with the -indeplist- command (downloadable from ssc)
you can get a list of all independent variables in your model, and
with the list extended macro function you combine these two list to
create a list of all _I variables that are in your model. See the
example below:
*-------------- begin example -----------
sysuse cancer, clear
stset studytime, fail(died)
gen randcat= ceil(3*uniform())
xi:stcox i.drug age i.randcat
indeplist, local
di "`X'"
unab all_I : _I*
local model_I : list all_I & X
di "`model_I'"
*-------------- end example -------------
(For more on how to use examples I sent to the Statalist, see
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )
Hope this helps,
Maarten
Ps. Notice that I created the variable randcat differently. You
created it by calling the function uniform() twice. That way
-uniform()>1/3- and -uniform()>2/3- can both be true since they
refer to different random numbers. More on this in Stata Tip 48
which will appear in the next Stata Journal. A pre-publication
draft is downloadable from my website.
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
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