Ex-Post Errors in Official Population Forecasts in Industrialized Countries
The existing literature on ex-post errors observed for historical population forecasts made by statistical agencies in 16 industrialized countries is reviewed. The amount and type of data in these studies (total population size, age structure, population growth rate, components of change), the level of detail (numbers of births and deaths, crude rates, total fertility rates, life expectancies), and the period covered vary considerably among the countries. Attention is given to forecast accuracy for total population size, population growth rates, fertility, mortality, the age structure, and the dependency ratio. Among the issues covered are relative errors for fertility and mortality, and common patterns across the countries. On the basis of a data set from Norway (covering the period 1969–1989), forecasts made between 1969 and 1987) and one from the Netherlands (for the period 1950–1986, forecasts made between 1950 and 1980) we investigate a possible correlation between forecast errors for fertility and mortality, and a possible reduction in forecast errors over time. The article concludes with suggestions for including results from ex-post evaluations in official population forecasts.
Demography; forecasting; population projections; accuracy; APC-model.