Shared frailty model (source code)

= Shared frailty model
{title2=$\lambda_{ik}(t)=Y_{ik}(t)V_i h_{0k}(t)e^{z_i^{\mathsf T}\beta}$}

A <shared frailty model> assigns the same latent positive hazard multiplier $V_i$ to correlated event histories or group members. Gamma or lognormal frailty distributions are common examples. Modeling dependence through this latent effect yields conditional covariate effects; integrating out frailty can change the form of marginal hazards. Eligibility and event history still have to be encoded in the at-risk indicator.