In this exercise we use data from a study of an intrauterine device (IUD) for prevention (Peterson, XXXXXXXXXXOne hundred women participated in the study and were followed for a maximum of 300 days....

In this exercise we use data from a study of an intrauterine device (IUD) for prevention (Peterson, 1975). One hundred women participated in the study and were followed for a maximum of 300 days. For each woman, the number of days from the insertion of the device to the first of the following events were recorded:

1) The IUD is expelled

2) The IUD is removed (for personal or medical reasons)

3) The woman is lost to follow-up (censoring)

The recorded times of these events are given in the table.

a) Describe the competing risks in this situation.

b) Compute and plot the Nelson-Aalen estimates
 for the cumulative cause specific hazard rates for causes h = 1,2 and interpret the plots.

c) Calculate and plot the cumulative incidence functions
 for causes h = 1,2 and interpret the plots.

d) Discuss the interpretation of the estimates in b) and c).