Combining Deterministic and Stochastic Population Projections

Population projections are sometimes requested for the assessment of the impact of population developments in the very long run. Such a long time horizon clearly undermines whatever meaning of forecast one would like to attribute to the projections results. Despite of that, users have the tendency to consider long-term projections not as one of the plausible developments of the population under given assumptions, but instead as an "almost sure" outcome. In order to raise the awareness of the users about the inherent uncertainty of population projections, the quantification of prediction intervals may play a very important role.