Model Tables: the Coale-Demeny set (cont.)

The Coale-Demeny model life tables are still the most commonly encountered system. The initial life tables were constructed for each family by sex and tabulated for various levels of mortality. Level 1 corresponded to an expectation of life at birth for females of 20 years. Subsequent levels of the life table reflected 2.5 year increments in female life expectancy, with level 24 representing a female life expectancy at birth of 77.5 years.

Subsequent updates to the Coale-Demeny tables extended the range to level 25. Further recent modifications have abandoned the notion of levels, extended the age range to 130, and re-presented the tables according to life expectancy at birth in one year increments for males and females separately. This last adjustment has other implications: in previous tabulations a given level (e.g. 17, corresponding to a female life expectancy at birth of 60) presented male mortality relative to female mortality. This is no longer the case and a life table for both sexes combined will have to be derived by choosing appropriate levels of male and female mortality separately.

A greater concern, however, lies in the suitability of the underlying patterns of mortality to contemporary populations; as child mortality has reduced in most parts of the world, the implicit connections between child and adult mortality incorporated in these tables may not be a good representation of underlying mortality experience. Nevertheless, these model life tables are still the most commonly used representations of mortality in most demographic analysis.