#Commands to Practical exercise 1
# Read the data into R:
melanoma=read.table("http://www.uio.no/studier/emner/matnat/math/STK4080/h08/computing/melanoma.txt",
header=T)
# Attach survival library:
library(survival)
# a) Nelson-Aalen plots for males and females:
fit.mel.a=survfit(Surv(lifetime,status==1)~sex,
data=melanoma, type="fl", error="ts",
conf.type="plain")
plot(fit.mel.a,
fun="cumhaz", mark.time=F, lty=c(1,2), xlim=c(0,10), xlab="Years
after operation", ylab="Cumulative hazard", main="Sex")
legend(0.5,0.55,legend=c("Females","Males"),lty=c(1,2))
# b) Nelson-Aalen plots for ulceration:
fit.mel.b=survfit(Surv(lifetime,status==1)~ulcer,
data=melanoma, type="fl", error="ts",
conf.type="plain")
plot(fit.mel.b,
fun="cumhaz", mark.time=F, lty=c(1,2), xlim=c(0,10), xlab="Years
after operation", ylab="Cumulative hazard",
main="Ulceration")
legend(0.5,0.8,legend=c("Present","Absent"),lty=c(1,2))
# With confidence intervals
plot(fit.mel.b,
fun="cumhaz", conf.int=T, mark.time=F, lty=c(1,2), xlim=c(0,10), xlab="Years
after operation", ylab="Cumulative hazard",
main="Ulceration")
legend(0.5,0.8,legend=c("Present","Absent"),lty=c(1,2))
# c) Nelson-Aalen plots for thickness
groups:
fit.mel.c=survfit(Surv(lifetime,status==1)~grthick,
data=melanoma, type="fl", error="ts",
conf.type="plain")
plot(fit.mel.c,
fun="cumhaz", mark.time=F, lty=c(1,2,3), xlim=c(0,10), xlab="Years
after operation", ylab="Cumulative hazard",
main="Ulceration")
legend(0.5,0.8,legend=c("0-1
mm","2-