[R] log-minus-log plot
marc_schwartz at comcast.net
Fri Feb 20 15:17:20 CET 2009
on 02/20/2009 07:23 AM Frank E Harrell Jr wrote:
> C.H. wrote:
>> Dear experts,
>> I would like to know how to plot the log-minus-log plot for survival
>> analysis (to check the proportional assumption) in R.
>> Using the AML example.
>> fit <- survfit(Surv(time, status) ~ x, data=aml)
>> length(fit$surv) #20
>> as the length of fit$surv is shorter than aml$x and aml$time. I don't
>> know how to plot.
>> Thank you.
> library(Design) # uses library(survival)
> fit <- survfit(. . .)
> survplot(fit, loglog=TRUE)
> ?survplot for details
Just to throw out another possibility, using a Cox model on the data:
fit <- coxph(Surv(time, status) ~ x, data = aml)
rho chisq p
xNonmaintained 0.0198 0.00691 0.934
# create plot. default transform = "km"
plot(cox.zph(fit, transform = "log"))
See ?coxph, ?cox.zph and ?plot.cox.zph in 'survival'.
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