Regression model to use. Choices are "ph", "po" or "aft"
shape
Baseline shape parameter
scale
Baseline scale parameter
lowerLimit
Lower censoring threshold
upperLimit
Upper censoring threshold
Details
Exact event times are simulated according to the given survival regression model.
Two covariates are used; x1 = rnorm(n), x2 = 1 - 2 * rbinom(n, 1, .5). After
event times are simulated, all values less than lowerLimit are left censored
and all values less than upperLimit are right censored.