THE ADDITIVE GENETIC GAMMA-FRAILTY MODEL

In this paper the additive genetic gamma fraility model is defined. In dividual frailties are correlated as a result of an additive genetic m odel, An algorithm to construct additive genetic gamma frailties for a ny pedigree is given so that the variance-covariance structure among i ndividual frailties equals the numerator relationship matrix times a v ariance. The EM algorithm can be used to estimate the parameters in th e model. Calculations are similar using the EM algorithm in the shared frailty model, however the E step is not correspondingly simple. This is illustrated re-analysing data, analysed by the shared frailty mode l in Nielsen et al. (1992), from the Danish adoptive register. Goodne ss of fit of the additive genetic gamma frailty model can be tested af ter analysing data with the correlated frailty model. Doing so, a ''de fect'' in the often used and otherwise well behaving likelihood was fo und.