Page 28 - IJPS-9-1

International Journal of
Population Studies Population aging and immigration in Japan

variable is the ratio of foreign resident population to show, fertility is the principal determinant of the age
the total population of Japanese nationals (F2J). The structure of a population, as noted in Section 1.2.1.
independent variables include the ratio of population by The data on the unemployment rate come from
age group to the total population (the term population the Statistics Bureau of Japan. The unemployment
refers to Japanese nationals unless otherwise stated), youth rate represents the number of unemployed people as a
dependency ratio or old-age dependency ratio. The control percentage of the labor force. Therefore, the rate is the most
variables include the TFR, unemployment rate, and hourly commonly used indicator for understanding conditions in
earnings of manufacturing. the labor market and the economy’s growth rate.
The data on the registered foreign residents population The data on the hourly earnings of manufacturing were
were obtained from the Ministy of Justice, Japan. Foreign obtained from the OECD. Goto (2007) observed that the
residents’ registration is a system used to record information majority of Nikkeijin foreign workers were employed in the
regarding foreign resident in Japan. Foreigners staying in manufacturing sector, as noted in Section 1.1. It is possible
Japan more than 90 days (tourists and persons who stay in that the hourly earnings of manufacturing are related to
Japan with a status of residence of “temporary visitor” are immigration in Japan.
exempted) are required to register. Therefore, the number
of registered foreign residents is a good proxy to measure 2.2. Methods
Japan’s immigrants. The empirical analyses in this study consist of the following
The population data by age group were obtained steps: (i) Graphical analysis, (ii) Augmented Dickey-Fuller
from the Statistics Bureau of Japan. Japan’s population (ADF) unit test, (iii) Pearson’s correlation, and (iv) an
age groups rely on historical birth registration, death ordinary least-squares (OLS) regression.
registration, estimates of migration into Japan, and A regression analysis that contains non-stationary
residence record system such as a Juminhyo system, which variables may produce misleading results. Therefore, ADF
is a registry of current registered addresses maintained by unit root test was employed to determine whether the time
the municipal governments. Japanese and foreign residents series were stationary. The precise definition of stationary
are required to report their addresses and related matters is that “the distribution of the time series variable does
to their municipal governments, who then compile the not change over time” (Stock & Watson, 2003, p. 446). If
information for tax, insurance, and census purposes. there are unit roots which are stochastic trends, the series
The age groups for this study are as follows: Ages 15 – is not stationary. If there are no unit roots, then the series
24, 25 – 34, 35 – 44, 45 – 54, 55 – 59, 60 – 64, and 65+ years is stationary.
old. For the ages between 55 and 64, 5-year age groups of Pearson’s correlation analysis was performed to describe
55 – 59 and 60 – 64 are included, because the 55 – 59 and the strength and direction of the linear relationship between
60 – 64 are the later working years, but the 60 – 64 is also the foreign residents and explanatory variables. In the next
early retirement ages. step, OLS regression was applied to analyze the relationship
The youth dependency ratio and old-age dependency between a single dependent variable and several independent
ratio were calculated using the population by age group. variables, while the other variables were held constant.
The youth dependency ratio at a given time is expressed
in percentage form as (population aged 0 – 14/population 3. Results
aged 15 – 64) × 100. The old-age dependency ratio at a 3.1. Initial results
given time is expressed in percentage form as (population Figures 1A–C provide the time-series plots of trends in
aged 65+/population aged 15 – 64) × 100.
demographic variables. In the figures, the x-axis represents
The data on the TFR come from the Ministry of Health, the year from 1975 to 2019. In the figures, the number
Labor and Welfare, Japan. The definition of the TFR is the of foreign residents decreased sharply in 2011 due to the
average number of children born to a woman in her lifetime tsunami on March 11, 2011. Figure 1A shows the fertility
(Siegel, 2002). TFR helps us project if a population size will rate decreased from 1.8 in 1984 to 1.3 in 2005, then started
increase, decrease, or stabilize over time. When the TFR is to rebound in 2006, and then began to decrease in 2016. The
greater than 2.1, the population in a given area will increase ratio of foreign resident population to the total population
if there is no out-migration. On the other hand, when the of Japanese nationals (F2J) seems to move negatively with
TFR is less than 2.1, the population in a given area will the fertility rate between 1975 and 2005. While the fertility
eventually decrease provided that there is no in-migration. rate trended downward, the F2J trended upward. The mean
As the demographic transition theory and the SDT theory TFR of 1.517 was below the replacement level of fertility.

Volume 9 Issue 1 (2023) 22 https://doi.org/10.36922/ijps.407