4 _Esffmatme and Poetios of Morality by Cause_

# Further details about the reliability of the data and the incorporation of estimates from subnationai information can be found in Annex A.

The reports on cause of death will be used as they are in tis paper, without attempdng corrections such as regrouping codes or reallocating the undefined causes. We rely on the original WHO procedures for scrutinizing the data before including them in their mortality database, and do not attempt any reclassification. Nor do we attempt the adjustments that might be needed to take associated or contributory conditions into account. It is difficult to nredict how the importance of associated causes will alter as countries progress throur,t the epidemiological transition. Certainly under the regime of infectious diseases, malnutrition will frequently underlie many deaths from diarrheel diseases or acute respiratory infections. On the other hand, as death Is increasingly postponed to older ages, multiple pathologies at or near the time of death become relatively common. As a result, this paper can only concem itself with reported distributions of underlying causes of death.

## _Estimating and projecting mortality_

Before estimating deaths by cause, overall mortality must be estimated and projected. This was done country by country, for 187 countries, territories, or groups of small countries or territories covering the entire world (but only aggregate results are reported). Life expectancy and infant mortality estimates for the 1985-90 quliquennium were obtained from the best available sources; adjustments were made as needed for agreement with other demographic parameters; and both forward and backward population projections were made.

Each country's experience with mortality change is used to project its mortality over the next three quinquennia (1990-2005), after which each country reverts to the average mortality trend for the world as a whole. This average trend involves slower improvements as life expectancy rises. The procedure involves separate projections of life expectancy (for each sex) and infant mortality (for both sexes combined), the imposition of nonlinear trends on both, and the choice of "split' life tables. Further description of the procedures is provided in Annex A.

The projections using these mortality trends are the 'standard' Bank projections (see Bulatao and others 1990). Two types of alternative projections were also run: 'fixed mortality' projections, in which age-specific mortality rates (for five-year age groups) are taken as fixed at 1985-90 levels throughout the projection period; and 'fixed distriution' projections in which mortality changes as in the standard projections, but the distribution of deaths by cause within each of the six larger age groups does not change from 1985. These alternative projections allow some decomposition of projected changes in the cause of death structure.

# _Predicting mortality rates by cause_

The equations for major causes of death predict mortality rates by cause from age and sex specific mortality rates for all causes. These equations are all lnear. Because some of the age groups covered a broad range of ages, slight variations in the equations