[R] How to obtain a 95% envelope for the estimated cumulative risk function from bootstrap samples

[wanr@ucalgary.ca]

Hi all,

I am trying to replicate the results from a paper. The problems are in the 
setting of survival analysis.

The hypothetical data is displayed as follows.

ID   time   status     
1     81       0 
2     42       1
3     37       1
4     54       0
5     35       0
6     38       1
7     29       0
8     40       0

Question 1: How to obtain a 95% envelope for the estimated cumulative risk 
function from bootstrap samples? I guess the output of this step consists of 
the envelope and the estimated cumulative risk function.

Question2: bootstrap process will be repeated for n times; then the average 
cumulative risk function was estimated  as the median of the n empirical 
cumulative risk functions. My question is how to plot this so called Average 
Risk Function vs. time easily instead of using lines() and points() to draw 
the above step function?

Thanks in advance.


Rui