The role of judgment,assumptions, techniques,and confidence limits in forecasting population

This paper discusses the fundamental role judgment and assumptions play in forecasting population. It is suggested that so-called “projections” operationally are usually either forecasts or extrapolations. Specific projection methodologies and techniques are shown to embody assumptions. A simple typology of such assumptions is presented as a guide to evaluate forecasts. Tests of projection technique accuracy are cited and it is concluded that such tests cannot succeed due to the assumption factor. Finally, time series forecasting techniques are criticized because their terminology with respect to confidence limits about a forecast is misleading.