Why do you suppose that that the United Nations gives high medium and low projections for future population growth, Why can they not give a single estimate? What factors should be consider in making these projections?© BrainMass Inc. brainmass.com October 9, 2019, 11:01 pm ad1c9bdddf
As the majority of world population growth is expected to occur in a handful of nations (see reference 2 below) these estimates take into account aspects of the demographics, predominantly, of these countries. That being said, any estimate (or growth model) is based on assumptions and these are by their nature imbued with varying degrees of uncertainty. For instance, developing nations are, by definition, changing (developing), so this degree of change ...
Answer discusses the inherent uncertainty in population estimation models.