In preparing the two sets of population projections it is necessary to make certain assumptions regarding the future course of migration, mortality, and fertility. The following assumptions were adopted for Projection A and Projection B:

Projection A

Migration

It is assumed that the population in Singapore is a closed population not subjected to international migration.

Mortality

It is assumed that the 1979–81 mortality level with a life expectancy at birth of 68.4 years for the males and 74.3 years for the females will improve over time to a life expectancy of 72.6 for the males by 2040 and a life expectancy of 75.2 by 200b for the females.

Fertility

It is assumed that the gross reproduction rate will rise from 0.841 in 1980 to 0.939 in 1985 and to 1.025 in 1990, after which it will remain constant at this replacement fertility level until 2070.

Projection B

Migration

It is assumed that the population in Singapore is a closed population not subjected to international migration.

Mortality

It is assumed that the 1979-81 mortality level with a life expectancy at birth of 68.4 years for the males and 74.3 years for the females will improve over time to a life expectancy of 72.6 for the males by 2040 and a life expectancy of 75.2 by 2005 for the females.

Fertility

It is assumed that the gross reproduction rate will remain constant below the replacement fertility level at the 1980 rate of 0.841 throughout the whole period of projection.