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Re: st: SE's on survival estimates from parametric models


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: SE's on survival estimates from parametric models
Date   Fri, 24 Apr 2009 16:57:30 +0000 (GMT)

--- On Fri, 24/4/09, Mark Hebblewhite wrote:
> My question is how to calculate the SE/95% CI for the
> predicted survival estimate from a parametric model in
> STATA. I know STATA is doing this with stcurve commands, but
> I haven't been able to figure out how to solve for a
> point estimate of survival and its SE for time t.  

In the example below I predict the hazard rate and it's CI at 
t=15. The se can also be predicted by specifying the -se()-
option in the -predictnl- command.

*--------------- begin example -----------------
sysuse cancer, clear
stset studytime, failure(died)
xi: streg i.drug age, dist(weibull)

local t = 15
local p "exp([ln_p]_b[_cons])"
local h0 "`p' *`t' ^(`p' -1)"

predictnl hazard = `h0' * exp(xb()), ci(lb ub)

twoway rarea lb ub age, sort || ///
       line hazard age, sort by(drug)
---------------- end example -------------------

Hope this helps,
Maarten

-----------------------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


      

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