Livstabell

Livstabell, the Swedish term for life table, is a statistical table used in demography and actuarial science to summarize the mortality or survival pattern of a population by age. It provides a concise view of how many people are alive at each age and how mortality changes across ages.

A life table typically lists ages and, for each age interval, the number of people alive at the start (l_x), the number who die during the interval (d_x), the probability of dying in the interval (q_x), and the life expectancy remaining at the start of the interval (e_x). Depending on purpose, tables may be cohort (generation) or period (cross-sectional) life tables.

Construction relies on mortality data from vital statistics or censuses. Period life tables use mortality rates observed in a specific time period, while cohort life tables follow a birth cohort over time. When data are limited, model life tables or smoothing methods are used.

Applications include pricing and reserving for life and health insurance, determining pension liabilities, and projecting population mortality for public policy.

Historical note: The concept dates to early actuarial science, with Halley’s 1693 life table as an influential early example; later work by de Moivre and others refined methods.

Limitations: life tables assume the rates observed in a period will hold; they are sensitive to data quality and to sudden mortality shocks such as epidemics or conflicts; modern life tables often provide confidence intervals and probabilistic projections.