The deviant dynamics of death in heterogeneous populations.
The members of most populations gradually die off or drop out: people die, machines wear out, residents move out, etc. In many such aging populations, some members are more likely to die than others. Standard analytical methods largely ignore this heterogeneity; the methods assume that all members of a population cohort at a given age face the same probability of death. This paper presents some mathematical methods for studying how the behavior over time of a heterogeneous cohort deviates from the behaviour of the individuals that make up the cohort. The methods yield some startling results: individuals age faster than cohorts, eliminating a cause of death can decrease life expectancy, a cohort can suffer a higher death rate than another cohort even though its members have lower death rates, and cohort death rates can be increasing even though its members' death rates are decreasing.-Authors
International Institute for Applied Systems Analysis, Research Report