Subpopulation Approximation

Synthetic two-country tests supported the practical accuracy of the leading approximation. Broader testing would be needed to fully determine when the correction term might become larger. The leading approximation is a female-death-weighted average of the subpopulation differentials. The study derived an exact decomposition for a total population made from two non-overlapping subpopulations. The correction term is expected to be small because it combines a small sex-share difference with observed lifespan differences.