Combining probabilistic and subjective assessments of error to provide realistic appraisals of demographic forecast uncertainty: Alho's approach

With increasing interest in forecast uncertainty, there is an evolving concern with assessing the degree of certainty we can attach to uncertainty itself. This concern is the subject of recent work by Juha Alho. This paper reviews his approach to tackling this problem. Alho focuses on conditional forecasts – conditional on the possible future policies feeding into the forecasts. This approach combines simple statistical methods with expert judgement to generate an overall predictive distribution for the future world population from 1994 to 2030. I examine the approach systematically and draw general conclusions about its efficacy. Suggestions for improvement are made.