splitpopsurv - Split-Population (Cure / Mover-Stayer) Survival Models

Maximum-likelihood estimation of split-population (cure / mover-stayer) survival models: an accelerated failure-time regression for event timing among "movers", combined with a logistic regression on the probability of belonging to the immune "stayer" population. Five baseline timing distributions are provided -- log-logistic, Weibull, log-normal, gamma, and the generalized gamma that nests the other four -- following Schmidt & Witte (1989, Journal of Econometrics) and Yamaguchi (1992, 1998, Sociological Methodology). This is an R translation of a set of Stata ml programs, with the log-likelihood corrected to match the published model and verified by simulation against known parameters.