  Although proportional hazard rate model is a very popular model to analyze
failure time data, sometimes it becomes important to study the additive hazard
rate model. Again, sometimes the concept of the hazard rate function is
abstract, in comparison to the concept of mean residual life function. A new
model called `dynamic additive mean residual life model' where the covariates
are time-dependent has been defined in the literature. Here we study the
closure properties of the model for different positive and negative ageing
classes under certain condition(s). Quite a few examples are presented to
illustrate different properties of the model.
