The Journal of Population Studies

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In this paper, we focused on the future old-age dependency ratio which is considered to be closely related to the financial situation of the Japanese public pension scheme, and analyzed the effect of the each component of the population change, i.e. birth, death or migration,on the old-age dependency ratio using variable-r method. Then we explored the effect of mortality improvement on the life cycle, defined a new old-age dependency ratio using the equivalent retirement age,and discussed the relationship with the public pension scheme. The main findings in this paper are as follows. ・In the analysis with variable-r method,we illustrated that the death factor is stronger than the birth factor,that means the mortality improvement between the cohorts gave large effect on the increase of the future old-age dependency ratio. ・Increase of the number of immigrants decreased the old-age dependency ratio as the decline in the migration effect.However,the effect became weakened over time since the immigrants themselves got older. At the same time, their births affected on the birth factor and decrease the old-age dependency ratio. ・We illustrated that the new old-age dependency ratio using the equivalent retirement age is lower than the usual ratio,and it succeeded to mitigate the variation of the ratio by mortality change. ・Recent mortality improvement could have produced a mismatch between the need and the level in the public pension benefit. Future mortality improvement might increase the degree of mismatch in the current pension scheme. The effect of each component of population change on the public pension scheme should be discussed from broader viewpoints. The quantitative analyses that were presented in this paper could be a basis for the discussion. It should become more and more important to discuss the public pension scheme based on these kinds of demographic analyses.

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This paper focuses on the low fertility of Sapporo and considers its demographic features among the designated cities by using Japanese Census and Vital Statistics in 2005. The important findings are as follows. 1. The cluster analysis shows 4 fertility patterns, "Industrial city"," Service industry city", "City with national average fertility" and "City with lowest low fertility" (Sapporo, Tokyo special wards). 2. The factor analysis indicates Sapporo's unique features. The proportion of married women and the marital fertility have almost same weight on low fertility and the catch-up effect realizing postponed marriage and birth by an advanced age does not work. 3. The different net-migration between male and female population causes the lowest sex ratio and the lowest first marriage rate of women in 15 cities at ages 25-29. This results again in the lowest singles sex ratio and the lowest first marriage rate at ages 30-34, so that the catch-up effect doesn't occur. 4. The negative correlation is observed between the mean age of woman at first childbirth and the proportion of the 3rd births in total births.Since the former has highly positive correlations with the mean age at first marriage, the late marriage in Sapporo could cause the late first childbirth and result in giving up to have the 3rd and more children.

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