How Much Do Mortality Differentials Affect an Accuracy of a Population Projection? Evidence from a Projection for Japanese Municipalities

Keita Suga, National Institute of Population and Social Security Research, Japan

We assess the role of mortality assumption under the population aging on the accuracy of population projections for the case of Japanese municipalities. Japanese society is the most advanced in terms of population aging in the world in 2010 and further population aging and decline is anticipated. Moreover, Japan is not the only country predicted for a future population decline, but more than one half of countries/areas in Europe and Asia is projected to lose their population in next fifty years. There are substantial variations in population aging among Japanese municipalities. This variation provide a source for the assessment of mortality effects on an accuracy of population projections. Results show that the forecast errors for the survival rates in 5 years beyond are negligible for the total population in the most of regions and at most 5% even for municipalities with less than 1,000 inhabitants.