# R-commands for non-parametric tests
# ===================================

# For illustration we will use the melanoma data 

# We first read the data:
melanoma=read.table("http://www.uio.no/studier/emner/matnat/math/STK4080/h12/melanoma.txt",header=T)

# We use the survival library, so this has to be loaded.


# To illustrate the two-sample tests, we test the null hypothesis
# that females and males have the same mortality (due to melanoma)

# First we use the logrank test:
survdiff(Surv(lifetime,status==1)~sex,data=melanoma)

# Then we try the Harrington-Fleming test with rho=1:
survdiff(Surv(lifetime,status==1)~sex,data=melanoma,rho=1)


# To illustrate the tests for more than two samples,
# we use the logrank test to test the null hypothesis that 
# the mortality is the same in all thickness groups:
survdiff(Surv(lifetime,status==1)~grthick,data=melanoma)


# To illustrate stratified tests, we use the logrank test to
# test the null hypothesis that females and males have the 
# same the mortality within each stratum defined by thickness group:

survdiff(Surv(lifetime,status==1)~sex+strata(grthick),data=melanoma)