Provide estimation and data generation tools for new multivariate frailty models.
This version includes the gamma, inverse Gaussian, weighted Lindley, Birnbaum-Saunders,
truncated normal, mixture of inverse Gaussian, mixture of Birnbaum-Saunders,
generalized exponential, Jorgensen-Seshadri-Whitmore, weighted Akash, weighted Shanker and
weighted Sujatha as the distribution for frailty terms. For the basal model, it
is considered a parametric approach based on the exponential, Weibull and the
piecewise exponential distributions as well as a semiparametric approach. For
details, see Gallardo et al. (2024)