Future Population Estimates Considering Interregional Migration

ABSTRACT

We estimate the population of each prefecture every five years up to 2050. The benchmark of our estimates is population data by gender and age among each prefecture from the 2005 Basic Census. Our implementation puts emphasis on the use of a transition matrix for inter-regional migration and on modeling birth and mortality rates as autoregressive processes.

According the results, the overall national population is expected at 118.8 million in 2025 and 92.15 million in 2050. We also find that the percentage of population over 65 will continue to rise from 20.1% in 2005 to 43.4% in 2050, and that the aging population trend will become more pronounced across all regions in the future. In addition, the degree of this aging population trend will differ significantly among regions: for example, we find that the elderly percentage will be roughly 50% in some prefectures while in other prefectures the ratio will remain at about 40%.