Agestructured

Agestructured (often written as age-structured or age-structure) refers to approaches in which individuals in a population are categorized by age and age influences demographic rates. The term is used across demography, ecology, epidemiology, and social sciences to describe models and analyses that recognize differences among age groups rather than treating the population as homogeneous.

In discrete-time settings, age-structured models use age classes with age-specific survival and fecundity; the Leslie matrix formalism is a well-known example, enabling projection of population vectors from one time step to the next.

In continuous-time settings, the McKendrick–von Foerster equation models the density of individuals by age as a function of time, with births determined by the age distribution and mortality rate by age.

Applications include population viability analysis, wildlife management, human demography, and stage- or disease-specific models, including age-structured epidemic models.

Data challenges include obtaining reliable age-specific rates, handling incomplete data, and accounting for aging and migration. Parameter estimation often relies on life tables, census data, and longitudinal surveys.

Limitations include model complexity, sensitivity to input data, and identifiability concerns.

See also: Leslie matrix, McKendrick–von Foerster equation, age-structured epidemic model.