Hi there,
Can anyone please help me because I am going to get crazy with the pbc data set.
I just want to apply simple cox regression in the data set. I am a beginner in R
but I don't think I am doing anything wrong.
I have the book of Fleming and Harrington 1990. I perform cox regression by
typing:
out<-
coxph(Surv(times/365,status)~log(bili)+log(proth)+edema+log(albumin)+age)
out
Call:
coxph(formula = Surv(times/365, status) ~ log(bili) + log(proth) +
edema + log(albumin) + age)
coef exp(coef) se(coef) z p
log(bili) 0.8636 2.3716 0.08294 10.41 0.0e+00
log(proth) 2.3868 10.8791 0.76851 3.11 1.9e-03
edema 0.8963 2.4505 0.27141 3.30 9.6e-04
log(albumin) -2.5069 0.0815 0.65292 -3.84 1.2e-04
age 0.0396 1.0404 0.00767 5.16 2.4e-07
Likelihood ratio test=231 on 5 df, p=0 n=416 (2 observations deleted due to
missingness)
Which is not exactly what fleming presents in table 4.6.3 page 195. Edema coef
is 0.8592.
I searched the net (please google: modern regression methods for survival data
stockholm)
and there some slides there. The results of the slides are again slightly
different and the analysis seems to be in R. So we all disagree. (I notice that
2 observation are excluded in my analysis, but not in the slides' analysis)
Also I check the age column, in the book the first two elemets are, 58.7652 and
56.4463 while in R 58.80548 56.48493. Age looks totally different.
Can anyone please help me. Also in the article "Survival model predictive
accuracy and ROC curves" , which is free just google it, in page 27 the
results seem to be different again. (caution with log(alb) or alb).
Does anyone has any information about this data set that clarifies things for
me??
Leo.
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