Cohort-based model vs. population-based model for mortality

Question

A cohort-based model groups individuals with at least one common characteristic over a period of time through a state-transition process. A population-based model reflects as much information as possible about a demographic of the target population. Based on these definitions, a population-based model should be preferred because (1.) the population model does not focus on a specific representative demographic and (2.) the population model is dynamic in the sense that it captures the entry of new groups to the target population.

My question is what the advantages of are using a cohort-based model over a population-based model are in the context of modelling mortality specifically in the management of longevity risk. Furthermore, how should a person choose between cohort and population model when designing a mortality model.

Answer 1

Your definitions are unusual. Where did you find them?

There are period and cohort life tables (models) - both refer to populations. A cohort model is a model where the cohort (i.e. year of birth) is an explanatory variable.

Including cohorts in mortality models makes a lot of sense since cohorts often carry predictive power. See for example here or this press article on the "golden cohort" in the UK. In most cases only cohort models are suitable for long term predictions of mortality. Period tables are only a snapshot of current mortality and less useful for predictions.