Dear R users:
I tried to use val.surv to give an internal validation of survival
prediction model.
I used the sample sources.
# Generate failure times from an exponential distribution
set.seed(123) # so can reproduce results
n <- 1000
age <- 50 + 12*rnorm(n)
sex <- factor(sample(c('Male','Female'), n, rep=TRUE, prob=c(.6, .4)))
cens <- 15*runif(n)
h <- .02*exp(.04*(age-50)+.8*(sex=='Female'))
t <- -log(runif(n))/h
units(t) <- 'Year'
label(t) <- 'Time to Event'
ev <- ifelse(t <= cens, 1, 0)
t <- pmin(t, cens)
S <- Surv(t, ev)
# I use cph instead of psm in the example
f <- cph(S ~ age + sex, y=TRUE)
w <- val.surv(f)
I got an error:
Error in survreg.distributions[[fit$dist]] :
attempt to select less than one element
Could some one explain for me?
Error in survreg.distributions[[fit$dist]] :
attempt to select less than one element
Error in survreg.distributions[[fit$dist]] :
attempt to select less than one element
*Yao Zhu*
*Department of Urology
Fudan University Shanghai Cancer Center
Shanghai, China*
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