The Place of the Hypothetical Generation in Modern Demography

On October 2, 2025, the International Laboratory for Population and Health held a seminar on "The Place of the Hypothetical Generation in Modern Demography."
Evgeny Andreev, head of the laboratory, presented a lecture on the history, advantages, and challenges of calculating demographic indicators using hypothetical generations.

Relevance

The lecture focused on the development of mortality study methods based on the concept of a hypothetical generation. It was noted that as early as the 17th century, John Graunt, in his work "Natural and Political Observations Made upon the Bills of Mortality…" (1661), first used hypothetical generation calculations, laying the foundations of demographic statistics. In the 19th century, this approach became more widespread and became the basis for modern life tables.

Today, life tables based on hypothetical generations remain the most widely used in both national and international statistical sources. In leading databases, such as the Human Mortality Database, life tables for real generations are significantly less common. This makes the hypothetical generation approach the most common method for demographic calculations, but also creates methodological limitations.

Statistical Issues and Methodology

The speaker noted that many mathematical models developed for hypothetical generations prove inapplicable to real generations. In particular, the Gompertz-Makeham law, which describes the probability of death at older ages, does not reflect this for real generations.

Particular attention was paid to the phenomenon of "rectangulation"—the narrowing of the mortality distribution around the ultimate age of survival. The speaker emphasized that this phenomenon is well described for hypothetical generations, but has not yet been sufficiently studied for real generations.

Graphical examples of age-specific mortality curves for various countries were presented. The comparison showed that the curves for real generations never match the curves for hypothetical generations, confirming the limitations of the latter.

Key Results and Conclusions

It was shown that calculations based on hypothetical generations reflect only the mortality rate in a specific calendar year and cannot describe processes occurring in real generations. For practical purposes in demography, it is often more appropriate to use standardized indicators, such as the age-standardized mortality rate and the standardized mean age at death.