[R] Confidence Intervals for survreg (survival)

annclaire ackovacs at millersville.edu
Sat Mar 7 15:29:34 CET 2015

I am trying to fit confidence intervals for my server object as well, but I
can only get an interval estimation for the intercept coefficient and am
getting NAs for my scale parameter.  Did you also have this issue?  
Below is a rough outline of my code

>newsurvobj <-Surv(studytimenew, censors)
> newserv <- survfit(newsurvobj~1, type="kaplan-meier")
> survreg(formula=newsurvobj~1, dist="weibull")
survreg(formula = newsurvobj ~ 1, dist = "weibull")


Scale= 0.4861742 

Loglik(model)= -160.8   Loglik(intercept only)= -160.8
n= 100 
> ??confint
> survival <- survreg(formula=newsurvobj~1, dist="weibull")
> confint(survival, level=.95)
               2.5 %   97.5 %
(Intercept) 2.540459 2.911843
confint(survival, "coefficients$scale",level=.95)
                   2.5 % 97.5 %
coefficients$scale    NA     NA

Thank you so much for any help you can offer!

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