Cohort-component population projections (cont.)
Calculations required in a population projection
Click below to see the steps required to project a population by means of the cohort-component method.
Calculate how many members of each living age cohort will survive the current projection interval.
Either add the immigrants to each age cohort and subtract the emigrants or, more simply, add net migrants to each age cohort.
Calculate how many births will occur during current projection interval and divide them into boys and girls.
Calculate how many of these births of each sex will remain alive at the end of the projection interval and adjust for net migration into the youngest age group.
Repeat the calculations for the next projection interval.
Note that the assumptions made about fertility, mortality and migration can be different for each projection interval. The method does not require an assumption of constant vital rates.