--- Michael McCulloch <[email protected]> wrote:
> Using the same simple stcox command, Stata 9.2 outputs the hazard
> ratio when I issue the command, but the coefficient when I use it
> within a program. I'd like to learn how to obtain the hazard ratio
> within my simple program.
<snip>
> . bootstrap, reps(1000): msmcox_stageII
The reason is not that you call -stcox- from within a program, but that
you use -bootstrap- on that program. -bootstrap- does not bootstrap the
coefficients that are displayed, but the coefficients that are returned
by -stcox-, and -stcox- returns the coefficients and not the hazard
ratio. The hazard ratio is exp(coefficient), so if you want to
bootstrap the hazard ratio you do:
*---------------- begin example -------------
sysuse cancer, clear
stset studytim, failure(died)
xi: stcox i.drug age
capture program drop test
program define test, rclass
xi: stcox i.drug age
indeplist, local
foreach var of varlist `X' {
return scalar `var' = exp(_b[`var'])
}
end
bootstrap age=r(age) _Idrug_2=r(_Idrug_2) /*
*/ _Idrug_3=r(_Idrug_3), reps(100): test
*--------------- 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 )
(this example requires -indeplist- which can be downloaded from -ssc-)
Hope this helps,
Maarten
-----------------------------------------
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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