This paper proposes a general framework to compare the strength of the dependence in survival models, as time changes, i.e. given remaining lifetimes , to compare the dependence of given >t, and given >s, where s>t. More precisely, analytical results will be obtained in the case the survival copula of is either Archimedean or a distorted copula. The case of a frailty based model will also be discussed in details.