Consider the MI study that you have analyzed. Suppose that we are interested in time to drop-out (i.e., time to censoring) from the study as the event of interest. 
(a) (10 points) Is time to drop-out censored in this study? Please explain why or why not, and if so, by what is it censored? 

(b) (10 points) Please estimate the distribution of time to drop out, i.e., P(D > t), where D denotes time to drop out. Please include 95% confidence intervals of any type and please identify which type of approximation you are presenting. Please include the code that you used to estimate this. 

(c) (10 points) Suppose you want to compare time to drop-out for those who are obese versus those who are not obese. Please display the Kaplan Meier estimates for each group and using a test of your choosing, formally test whether the distributions differ between these groups