**XuoXVI INTOROUC1ON**

in which me model patterns are not applied is the base period, for which current or recent fertility data **an** used.

These procedures were developed from analysis of total fertility trends in cross-national data (see Bos and Bulatao 1989). Their application results in only minor deviations from fertility trends projected in last year. Fertility trends from the current and last year's projections and<sup>the</sup> U.N. projections are compared in Figures A6 and A7 for low developed countries and<sup>more</sup> developed countries. Bank fertility projections show little change from last year, with the current projection for low developed countries being only slightly slower until around 2025. The U.N. projects higher levels of fertility for low developed countries between 1990 and 2005, and lower levels thereafter. The U.N. and Bank projections differ more for more developed countries trends. The U.N. projects that fertility, now below replacement level for these countries as a whole, will not fall much further but will return to replacement level more slowly than in the current projections.

## _Prviedln Migrwtox_

Estimates of future net migrants by quinquennium up to the year 2000 are those prepared by Arnold (1989) as part of an examination of data and sources, with subsequent minor revisions. These estimates are strongly affected by official policies and plans in the major receiving countries. The figures were designed to total zero in each quinquennium for the whole world. After the year 2000, the number of net migrants is assumed to approach zero linearly in each country, at the estimated rate of change in their number from the period 1990-95 to the period 1995-2000, or at a rate that would make their number zero by 2025-30, whichever rate is faster. For these later periods, **a** zero total for worldwide net international migration was obtained by adjusting initial estimates of net migats in three major receiving countries--the United States, Australia, and Canada--upward or **downwrd as** necessary by a proportion constant across these countries, but varying by quinquennium. These adjustments were of I or 2 percent for the earlier periods, negligible compared to the volume of migration assumed for these countries, but were up to 10 percent for '-ter periods.

The age-sex distributions of migrants are determined rrom alternative models based on their sex ratios. If migration is heavily male, migrants are assumed to be conceitrated in the age group 15-29, with few children and elderLy. If migration is more balanced oetween males and females, proportionally more migrants are assumed to be children and elderly (Hill 1990).

# REFERENCES

Arnold, Fred. 1989. Revised estimates and projections of international migration. Policy, Planning, and Research Working Papers, No. 275. Washington, D.C.: World Bank.

Bour-eois-Pichat, Jean. 1952. Essai sur !la mortalite biologique de l'homme. Population 7(3) Bourgeois-Pichat, Jean. 1978. Future outlook for mortality decline in the world. _Population BuUetin of the United Nations._ 11: 12-41.

Bos, Eduard, and Rodolfo A. Bulatao. 1989. Projecting fertility for all co; ntries. Policy, Planning, and Research Working Pape1s. Washington, D.C.: World Bank.

Blum, Alaiim, **and** Roland Pressat. 1987. Une nouvelle table de mortalite pour l'URSS (1984-1985). _Population_ 42(6):843-862.

Bultac, Rodol;o A., and Eduard Bos, with Patience VW. Stephens and My T. Vu 1989. Prc,ecting mortality for all countries. Policy, Planning, and Research VWorking Papers. 'Nashington, D.C.: World Bank.

Bulatao, Rodolfo A., Eduard Bos, Patience Stephens and My T. Vu 1990. _World Population Projections. 1985L90 Edision._ Jobns Hopkins University Press. Baltimore Maryland. **Bulatw, Rodolfo** A., **and** Ann Elwan. 198S5. Fertility and mortality transition: Patterns, projections, and interdependence. World Bank Staff Working Paper No. 681.