4 U.N. 1984 assessment. Other sources of mortality data include Eurostat (1987), the U.S. Bureau of the Census (1985), Celade (1987), and various surveys. These sources often report mortality levels for periods other than 1985-90, or give indices other than life expectancies, or both. Some estimation and projection is then necessary to obtain the right index. In some cases, a mortality estimate is made first for an earlier period, and an estimate for 1985-90 obtained by applying the projection methodology being described here. Some Bank sources are also cited in the Appendix: Bank sector reports; Bank assessments, involving unpublished analysis of census or survey data; and Bank estimates, or informed judgments for which no further source can be cited (see Appendix).

The future trend in mortality in all countries was represented by steady increments to life expectancy, with smaller increases at higher life expectancy levels, and with different schedules of increments where few or where many females are in school.

The schedules of increments for female life expectancy were developed in earlier analysis involving regressions of change in female life expectancy between 1965-69 and 1975-79 on initial life expectancies in 196569, separately for countries with different levels of female enrolment. Life expectancies were obtained from Bank files and female primary school enrolment in 1965-69 from Unesco (1977). Female enrolment was used as a control because preliminary analysis confirmed a strong relationship (R<sup>2</sup> _ 0.50 over 30 developing countries) of female enrolment with current life - expectancy and a slightly stronger relationship (R<sup>2</sup> 0.53) with life expectancy lagged ten years. Countries were divided into two female enrolment groups: those with female primary school enrolment of 70 percent or more and those with female primary school enrolment of less than 70 percent.

Figures 1 and 2 plot changes in female life expectancy against initial levels for the two groups of countries. Also plotted are lines estimated through quadratic regression. The line for the low female enrolment group is almost linear. Female life expectancy was below 55 in all countries in this group (with the exception of Saudi Arabia, which was considered an anomaly and is not represented). We assumed that the increments to life expectancy in this group would increasingly approximate the increments in the high female enrolment group once life expectancy passed 55. This produced a single unified schedule of increments diagrammed in Figure 3 and listed in Table 1.

Hale life expectancies were projected either by applying roughly the same schedule of increments as female life expectancies or by first selecting female life tables and then adopting for males the parallel life tables of the same level and family. In either case, the maximum life-table level for males was set at one below the equivalent female level, imposing a slower improvement in male life expectancies. Life tables were chosen from among the Coale-Demeny models to provide the age distribution of deaths. These model life tables come in four families--North, South, East, and West--each of which has 25 levels. A