The United Nations Probabilistic Population Projections: An Introduction to Demographic Forecasting with Uncertainty

Abstract

The United Nations publishes projections of populations around the world and breaks these down by age and sex. Traditionally, they are produced with standard demographic methods based on assumptions about future fertility rates, survival probabilities, and migration counts. Such projections, however, were not accompanied by formal statements of uncertainty expressed in probabilistic terms. In July 2014 the UN for the first time issued official probabilistic population projections for all countries to 2100. These projections quantify uncertainty associated with future fertility and mortality trends worldwide. This review article summarizes the probabilistic population projection methods and presents forecasts for population growth over the rest of this century.

Figure 1. Population Projections for Burkina Faso

Figure 2. Illustration of the Three Phases of the Model for Total Fertility

Figure 3. Illustration of Decline Function Used to Project Expected Declines in the TFR during the Fertility Transition (Phase II)

Figure 4a. Decline Functions for Burkina Faso

Figure 4b. The TFR Projections for Burkina Faso

Figure 5. Population Projections for 2100

“B” denotes Billion and “M” denotes Million. Numbers shown with Area Names are the Population Projections for 2100 with 80% Prediction Intervals.