_Estimates and Projections of Mortality by Cause_ _26_ possible to the ratio for that country. The second step is to make up composite or 'split' life tables from life tables for different levels of the selected family: the infant mortality rate is used to select levels to apply up to age 14, and the life expectancies are used in conjunction with the first selection to select levels to apply from age 15 on. By the thirteenth quinquennium, all countries are assumed to have reverted to West model life tables, with levels chosen according to the median trend in life expectancies and infant mortality determined entirely by the choice of levels. Between the third and the thirteenth quinquennium, life tables are interpolated to provide a smooth transition.

Single-year deaths by age and sex are obtained by interpolation from the quinquennial estimates normally provided in the projections, taking migration into account.

For more detail and justification of these procedures, a background paper on the World Bank projection procedures (Bulatao and Bos 1989) can be consulted.

# _Predicting deaths by major cause_

The equations for major causes of death show mortality rates by cause increasing with overall mortality for all causes except neoplasms. The increases are greatest for infectious and parasitic diseases (slopes around 0.5, meaning that half of an increase in deaths is attributable to this major cause), followed by other and unknown causes (slopes around 0.25) and perinatal conditions (slope of 0.22, for age group 0 only). Slopes vary considerably by age group: for infectious and parasitic diseases, they vary from 0.7 for those 14 years old to 0.4 for those 65 and older. Slopes also vary by sex: for neoplasms among those 65 and older, the slope for males is -0.13 and for females -0.04. Nevertheless, the trend across age groups is essentially similar between males and females. In contrast, slopes vary very little across regions, with the largest gap between regions for a given cause and sex and age group being around 0.04. The equations for lower-mortality, more developed regions do appear to diverge more often from the norm, though ordy minimally. Considering the number of regions and the rarity of even small differences in the equations, the case for distinct cause of death structures across regions is weak.

Where reported data were not available, the equations specific to each of the 24 regions were applied (though the world equations would produce similar results). For 2000 and 2015, we maintained the same region-specific equations for the industrial market economnies but allowed each other country to switch from its region-specific set of equations to the equations for developed countries as a whole if its mortality level had declined sufficiently, as indicated by a crude death rate, standardized using the 1985 age structure for the world as a whole, below 6. (The industrial market economies as a group have a standardized crude death rate of 5.8, as contrasted, for example, with 9.0 for Latin America and the Caribbean.) The few negative estimates of mortality rates (e.g., because of the negative slopes for neoplasms) were set to zero case by case, and rates for other disease categories adjusted proportionally.