Definition:Life table
📉 Life table is a statistical tool used extensively by actuaries and life insurers to model the probability that individuals of a given age will survive to, or die before, each subsequent age. Sometimes called a mortality table, a life table provides the foundational data from which premiums, reserves, and death benefit obligations for life insurance and annuity products are calculated.
🔢 Construction of a life table typically starts with a hypothetical cohort — say, 100,000 individuals at age 0 — and applies age-specific mortality rates derived from population data or insured-lives experience to track how many survive to each subsequent year. Key columns include the probability of dying within a given year (qx), the number of survivors (lx), and the expected remaining lifetime at each age. Insurers use both period life tables, which reflect mortality rates at a single point in time, and cohort life tables, which project how mortality will improve over a generation. The Society of Actuaries and the NAIC publish standard tables — such as the Commissioners Standard Ordinary (CSO) tables — that carriers use for statutory reserving and regulatory compliance, while individual companies often develop proprietary tables reflecting their own underwriting experience.
🧮 Accurate life tables are indispensable because even small deviations in assumed mortality can compound into large financial impacts over the long durations typical of life insurance contracts. An insurer that relies on outdated tables may systematically underprice term life coverage or over-reserve for annuity payouts, misallocating capital in either case. As medical advances, lifestyle changes, and demographic shifts alter mortality patterns, the industry must periodically update its tables — a process that involves extensive data collection, statistical analysis, and regulatory review. Life settlement investors and reinsurers similarly depend on refined life table data to model portfolio performance and manage longevity risk.
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