Practical exercise 1
In this exercise we will see how Nelson-Aalen plots may be used to study the effect of various covariates for the lung cancer data given at the course web-page.
a) Look at the commands given at course web-page for reading the data and computing Nelson-Aalen plots for all patients and separately for males and females. Perform these commands and interpret the results.
Make Nelson-Aalen plots according to the categorical covariates
b) actitvity score
c) anorexia
d) hoaresness
e) metastases
and interpret the plots.
Age is a numeric covariate. In order to make Nelson-Aalen plots that show the effect of age, we need to make a categorical covariate for age. This can be achieved by the command "cut" (give the command "help(cut)" to see how "cut" is working).
f) Make Nelson-Aalen plots that show the effect of age and interpret the plots.