Displaying 2 results from an estimated 2 matches for "lalountas".
2005 Aug 27
1
survival parametric question
...ee" the accelerating-decelerating effect in the AFT case.
In addition how can simulate a model in the AFT case ( some examples of simulation are given in the design manual for the COX-PH case.
I hope that my questions are not borring, if so sory I am a new user of R package.
Best regards
D.Lalountas
University of Patras , Greece
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2007 Jun 28
0
WEIBULL FRAILTY MODEL HELP
...eto^(p[2]-1))/p[1]))*stat
lik <- p[3]*log(p[3])-log(gamma(p[3]))+sum(lnhaz)+
log(gamma(di+p[3]))-(p[3]+di)*log(p[3]+cumhaz)
-2*lik
}
di <-sum(stat)
initial<-c(500000,2.8,.5,1.8)
# initial 1/exp(constant)
t<-nlm(likelihood.weibul,initial,print.level=1,hessian=T)
Best Regards,
Denis Lalountas
University of Patras
insem<-read.table("Melanoma.txt",header=T)
id <- insem$id
timeto<-insem$time
stat<-insem$status
x1<-insem$ulcer
x2 <-insem$thickness
x2 <- log(x2)
id time status sex age year thickness ulcer
1 1 10 0 1 76 1972 6.76 1...