ABSTRACT
This chapter discusses the progress and factors of population aging in the Tokyo metropolitan area in the first half of the 21st century. The following hypothesis was established in the discussion: the speed of the rise in Japan’s aging rate in the first half of the 21st century strongly depends on the size of the cohort newly entering the elderly population during the relevant period. This hypothesis was verified using demographic approaches. The most important results obtained through the verification process can be summarized as follows:
A correlation analysis was conducted between the size of the cohort by prefecture at the beginning of a period and the change in the aging rate by prefecture during the period. We found a strong positive correlation between them for both cohorts, including the first and second baby boomers. However, a stronger correlation was observed for the immediately preceding cohorts of the two. This means that the above hypothesis has been demographically verified. On the other hand, when considering the contribution to the change in the aging rate, the baby-boomer cohorts were found to have a much larger contribution than the immediately preceding cohorts. These results indicate that although the rise in aging in the Tokyo metropolitan area during the first half of the 21st century is largely due to the contribution of the baby-boomer cohorts, the factor that makes this rise significantly higher than in other areas is the strongly biased distribution of the immediately preceding cohorts toward the Tokyo metropolitan area.
