A list with three objects (a) X, a dataframe with n rows representing clinical subjects and columns:
treatment, x1, x2, x3 and x4 where treatment is binary indicating the two arms of the clinical trial
and x1, ..., x4 are covariates that were collected about each subject (b) y, a length n vector storing
the survival response values (a time measurement) where, in this mock dataset, smaller values indicate "better"
survival outcomes for the subjects and (c) censored, a length n vector storing the censor dummies where
c_16 = 1 means the response y_16 was censored and thus the truth value of y_16 is unknown and y_16 only represents
the moment it was censored (and c_16 = 0 means it was uncensored and y_16 is the true response value).