Population Forecasting - Principles and General Procedures

In general, data bases in developing countries on population development are limited. Simple population projections are, therefore, the only possible population forecasts.

For a simple population forecast, using a spreadsheet programme (e.g. Excel) the following steps are recommended:

1. Take the latest and the previous population census for the region (usually a census is undertaken every ten years).
2. Calculate the annual growth rate between these censuses.
3. Apply this annual growth rate to calculate the future population for the region e.g. for a five, ten year, or fifteen year period of time.
4. For population figures above 10,000 the figures are usually rounded up to the next 1000 (e.g. 47,538 becomes 48,000) and if the figure is below 10,000 then it is rounded up to the next 100 (e.g. 2,871 becomes 2,900).

This simple population forecast will provide a continuation of the current trend, it disregards both natural and economic changes of the population development, which generally influences migratory patterns.

In order to develop an “improved” population forecast the following steps should be undertaken:

1. Take the latest available census of population for your country and the previous census.
2. Calculate the annual growth rate between theses censuses
3. Take the latest available census of population for your region and the previous census
4. Calculate the annual growth rate between theses censuses
5. Compare the growth rates; the difference will give you information on the migration to or from your region
6. Apply the annual growth rates to calculate two variants of the future population of your region, variant 1 with natural population increase, variant 2 with natural population increase plus migration

The improved population projection will provide a population range for the projected period of time (either five, ten or fifteen years).

In order to be able to further improve the quality of the projections it is worth making use of any demographic data that is available in the country (i.e. UN Demographic yearbook, statistical yearbook, etc.). In most cases assumptions have been made about the future demographic trends e.g. the expected development of the birth rates (as a result of family planning work) as well as death rates (due to health improvement programmes). Taking this data one can adjust the annual growth rates for the future and apply them in the population projections.

As soon as new census data is available, the existing projections have to be updated on the basis of the new data.