A Gamma Frailty in Bivariate Survival
We consider a bivariate survival model with the presence of a unobserved random covariate, frailty, that induces dependency between the failure times and acts according to a proportional hazard model. We consider gamma distribution for this frailty and Weibull marginal distributions and we introduce explanatory covariates that act according to an accelerated life model. We consider covariates in association parameter.
Key words: Bivariate Survival, Frailty, Proportional hazard, accelerated life, Weibull, Estimation.