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# Re: st: Predicting survival at a specific time following generalized gamma regression

 From Steve Samuels <[email protected]> To [email protected] Subject Re: st: Predicting survival at a specific time following generalized gamma regression Date Wed, 11 Jul 2012 10:01:18 -0400

```Instead of

*******************
predict t_surv, surv
********************

try
*****************************************
predictnl t_surv = predict(surv),  ///
se(se_surv) ci(low_surv up_surv)
*****************************************

Steve
[email protected]

On Jul 11, 2012, at 7:24 AM, Thomas Inns wrote:

Hello,

If someone could kindly take the time to help me I'd be very appreciative. I'm try to predict the probability of survival at one year following infection.
I'm using a parametric survival model with a generalized gamma distribution and an accelerated failure-time metric (streg, distribution(gamma) time).

I have used the streg postestimation command "predict, surv", but I can't work out how to put a confidence interval around my predicted survival probability at one year following infection. Is this possible? And if so, do you know how I might do this?

Below is my code, inspired by Bobby Gutierrez's post at http://www.stata.com/statalist/archive/2010-12/msg00647.html.

Thanks,
Thomas Inns

*************CODE BEGINS*************
streg i.ribolog i.gender i.agetri i.year i.ftbin##i.trustapp, d(gamma) time

****predict conditional survivor function (probability of survival past time t)
****(time t = 1 year)
*prediction at t = 365.25
gen tt = 365.25

*keep old _t
gen t_old = _t

*put in _t you want to use for prediction
replace _t = tt

*predict surival past time _t (one year)
predict t_surv, surv

label var t_surv "gamma prediction"

*summarise these predictions
summ t_surv, detail
**************CODE ENDS**************

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