Cohort life tables track the mortality experience of people born in each year from 1876. These complement the more common period life tables which show the mortality experience in a specific time period.
The cohort mortality data presented here will be updated and extended annually. Summary results will also appear in the annual reference volume Demographic Trends (from 2006).
For technical details on the derivation of the cohort life tables see A History of Survival in New Zealand: Cohort Life Tables 1876–2004.
Notes to users
Users of the cohort life tables should note the following:
- The derivation of the cohort life tables required the application of various data estimations and assumptions. The mortality history of each birth cohort has been built up from births, deaths, and migration data which vary in coverage and completeness over time. Care should be exercised when interpreting the cohort mortality tables to avoid over-precise comparisons, especially between adjacent birth cohorts and at the oldest ages where the cohort populations are small. The cohort mortality results are subject to ongoing revision as additional births, deaths, and migration data becomes available.
- The births and deaths data presented in this cohort mortality study will differ from that used in other fertility and mortality statistics. The study is based on all (live) births and deaths occurring in New Zealand according to the year they occurred, in addition to war deaths occurring outside of New Zealand. The population denominators for the study were derived solely from the components of population change (estimated births, deaths, and external migration). In contrast, other fertility and mortality statistics (eg annual fertility rates, period life tables) are based on (live) births and deaths occurring in New Zealand according to the year they were registered. Since 1991, the published statistics have also excluded events to people visiting from overseas. The population denominators for those statistics are derived from census counts.
- The projection of cohort death rates at ages above 74 years is designed to extend the mortality analysis for cohorts who have not yet completed their life span. By this extension, 1936 is the latest birth cohort for whom life expectancy can be calculated. In presenting the results of cohort life tables, projected life table data are distinguished from historical data by the use of italics in tables and dashed lines in figures.