The impact of forecasting methodology on the accuracy of national population forecasts: Evidence from the Netherlands and Czechoslovakia

This study considers the accuracy of national population forecasts of the Netherlands and the Czechoslovak Socialist Republic (CSSR) produced by the statistical agencies of these countries after World War II. Attempts are made to link patterns of ex‐post errors to changes in forecasting methodology. We look at the demographic components employed in each forecast, the procedure to extrapolate fertility and the level at which assumptions for each component are formulated. Errors in total population size, fertility, mortality and foreign migration, and age structure are considered. We discuss trends in errors and methodology since 1950 and compare the situations in the two countries. The findings suggest that methodology has only a very limited impact on the accuracy of national population forecasts.