Baseline survival function for mixture cure model
S0(t, pi0, survdist, k, lambda0)time variable
cure rate for the control arm, which is between 0 and 1.
survival distribution of uncured patients. It can be "exp" or "weib".
if survdist = "weib", the shape parameter k needs to be specified. By default k = 1, which refers to the exponential distribution.
scale parameter of exponential distribution or Weibull distribution for survival times of uncured patients in the control arm.
The density function of Weibull distribution with shape parameter k and scale parameter \(\lambda_0\) is given by
$$f(t)=\lambda_{0}k(\lambda_{0}t)^{k-1}\exp(-(\lambda_{0}t)^k),$$ for \(t > 0\),
and the corresponding survival distribution is
$$S(t)=\exp(-(\lambda_0 t)^k).
$$