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CHAPTER 2 POPULATION AND HOUSEHOLDS
This chapter covers population, households, vital statistics and migration.
The section of population contains statistics on the basic attributes of population such as the size and growth of population, its geographical distribution, its structure by sex and age, etc. The principal sources of data are "Population Census" taken quinquennially by the Statistics Bureau, Ministry of Internal Affairs and Communications. Data for the intercensal years and the estimates of future population are obtained from "Population Estimates" by the Statistics Bureau, Ministry of Internal Affairs and Communications and "Future Population Projections" by the National Institute of Population and Social Security Research, respectively. Also available are "Statistical Survey on the Japanese Nationals Overseas" compiled by the Ministry of Foreign Affairs, "Statistics on Foreign National Residents" compiled by the Ministry of Justice, concerning data on the Japanese living abroad, and the number of foreign national residents respectively.
The section of household contains statistics on various attributes of households such as geographical distribution, size of household, type of household, etc., whose statistical source is the "Population Census" mentioned above.
The section of vital statistics contains statistics on live births, deaths, foetal deaths, marriages, divorces, etc., which are derived from "Vital Statistics" and "Life Tables", both compiled by the Ministry of Health, Labour and Welfare.
The section of migration contains statistics on changes in the place of residence within the country, entries into and departures from Japan, and daily commuters and students. Data are mainly obtained from "Internal Migration in Japan Derived from the Basic Resident Registers", of the Statistics Bureau, Ministry of Internal Affairs and Communications, and "Statistics on Legal Migrants", of the Ministry of Justice, in addition to the "Population Census" mentioned above.
Population prior to the Population Census
The first Population Census in Japan was taken in 1920. Prior to that time, the Population Estimates had been compiled by the Cabinet Bureau of Statistics since 1872.
The population from 1872 to 1898 was estimated annually on the basis of the permanent domicile population as of 29 January 1872 in the lunar calendar (8 March in the solar calendar), by adding registered live births, deserted children and new registrations, and subtracting registered deaths and removals from registry as well as the number of Japanese nationals living overseas as of the end of year.
The population of 1899 and following years is estimated retroactively on the basis of the population of the Japanese nationals in Japan proper, obtained from the Population Census taken as of 1 October 1920, by adding to or subtracting from it the live births, deaths, deserted children, new registrations, removals from registry and overseas migration of Japanese nationals, which had occurred before the end of September 1920.
The above two estimated population series were adjusted for smooth linkage, first by allotting the discrepancy between the two series for the year 1899 proportionately according to the respective magnitude of increase during the period from 1872 to 1898 and the period from 1899 to 1920, and secondly by allotting them proportionately according to the magnitude of increase during each year.
Population Census (Fundamental Statistical Survey)
The Population Census has been taken every five years since 1920, with one exception, to ascertain the situation of the population of the country. The nineteenth census was conducted in 2010. An exception is the sixth census, which was originally scheduled for 1945 but suspended owing to the hard conditions of the war, and was replaced by the Extraordinary Population Census in 1947. The censuses up to the fifth (1940) were based on "Act Concerning the Population Census", whereas those after the sixth were taken according to the provisions of the "Statistics Act ".
From the first census to the sixth, population were enumerated as the de facto population. However, from the seventh census (for 1950) to the present, the principle for enumeration is the de jure concept.
The census data of Okinawa during the period of 1950 to 1970 are based on the census results which were conducted by the U.S. Military Government in Ryukyu Island (for 1950 census) and the Government of Ryukyu Island (for 1955 to the 1970 census). However, the 1945 Population Census and the 1947 Extraordinary Population Census were not conducted in Okinawa. Therefore, the population of Okinawa is not available for those years.
The Census covers the whole territory of Japan, but excluding Habomai Islands, Shikotan Island, Kunashiri Island, Etorofu Island and Take-shima are not surveyed.
The 2010 Population Census covered all the persons usually living within the territory of Japan as of 1 October and was conducted by the self-enumeration method (partly filled out by the enumerator) through the channel of the Statistics Bureau, Ministry of Internal Affairs and Communications; prefectures; shi (cities), ku (wards), machi (towns) or mura (villages); census supervisors and census enumerators.
The tabulation results are compiled by several stages, Preliminary Tabulation, Basic Complete Tabulation, Tabulation on Place of Work or Schooling, etc.
Densely Inhabited Districts (DID's)
DID's were established for the first time in the 1960 Population Census, taking into consideration the large scale merger of shi, machi, and mura in the preceding years which had made the urban-rural classification obscure.
A DID is defined as an area, <1> using census-enumeration districts as the basic unit block of area, <2> composed of a group of contiguous census-enumeration districts with high population density (in principle, 4,000 inhabitants or more per square kilometre) within the boundary of a shi (city), ku (ward), machi (town) or mura (village), <3> constituting an agglomeration of 5,000 inhabitants or more as of the date of the census.
This classification, which was first introduced in the 1970 Population Census to ascertain social and economic characteristics of the population, is a combination of labour force status, occupation and employment status. For the classification concerning labour force status, etc., see "19 Labour and Wages".
Type of household
A private household is defined as a group of persons sharing living quarters and living expenses, a person who lives by himself / herself in a dwelling unit, a person residing together with other persons but keeping a separate budget, a person residing in a boardinghouse, or a person who lives in a dormitory for unmarried employees of a company, corporation, store and government, etc.
An institutional household is <1> students in school dormitories, <2> inpatients of hospitals, <3> inmates of social institutions, <4> persons in camps of Self-Defence Forces, <5> inmates of reformatory institutions, or <6> others (persons who have no fixed residence or crews who have no residence on land).
In 1980 and before, however, households were sub-divided into ordinary households and quasi-households. An ordinary household referred to the private households excluding single persons who lived in company dormitories for unmarried employees.
In addition to the population information from the quinquennial Population Censuses, Current Population Estimates is compiled for intercensal years by the Statistics Bureau, Ministry of Internal Affairs and Communications. With respect to the population of the whole country, the total population on the first day of every month and the population classified by age group as of 1 October of each year are estimated from the enumerated population in the Population Census, by adding to or subtracting live births, deaths and entries into and departures from Japan, that occurred thereafter. And for the population of prefectures, the estimates as of 1 October of each year are obtained by further adding or subtracting migrants between prefectures. When a discrepancy occurs between the estimated population and the figure enumerated in the next Population Census, the estimates are adjusted retroactively to agree with the census figures. Data on births and deaths are obtained from "Vital Statistics", the numbers of entries into and departures from Japan by "Statistics on Legal Migrants", and the numbers of migrants between prefectures by "Internal Migration in Japan Derived from the Basic Resident Registers".
Future Population Projections
Population projections are prepared by the National Institute of Population and Social Security Research based on the results of the most recent Population Census. The latest projection was made in January 2012, covering 50 years from 2011 to 2060. In addition, extra-long-term estimates covering 50 years from 2061 to 2110 are presented for reference. Using the 2010 Population Census as the base, population projections are made by calculating the number of survivors of the base population in the future years, and for the newly-born population, by calculating the number of survivors of the live births estimated for the future years.
Vital Statistics (Fundamental Statistical Survey)
Vital statistics have been compiled in Japan since 1872. Subsequently in 1899, the Cabinet Bureau of Statistics took charge to bring the survey into conformity with the Family Registration Act as amended in 1898. Then in 1945, at the time of the end of the war, the survey system was completely revised. In September 1947, the jurisdiction of the statistics was transferred to the Ministry of Health and Welfare (now, the Ministry of Health, Labour and Welfare).
Vital statistics are tabulated from the report of every registered of live births, deaths, marriages, divorces or foetal deaths through the head of shi (city), machi (town) or mura (village) pursuant to the provisions of the Family Registration Act and the Regulations Regarding Declaration of Foetal Deaths. Statistics presented in this Yearbook are limited to the events occurred to the Japanese living in Japan. The population used for the computation of vital rates is the Japanese population as of 1 October of the year from the Population Census or the Population Estimates mentioned above. However, the population used for years before 1966 is the total population including foreigners.
Infant deaths refer to those that occurred within a year after birth. Neonatal deaths refer to those within four weeks after birth, and early neonatal deaths, to those within a week.
Foetal death refers to the delivery of a dead child after twelve full weeks of gestation (or the fourth month of gestation), and a dead child is defined as a child whose heart pulsation, movement of voluntary muscles and respiration are not perceived after delivery.
Standardized vital rates
The ratio of live births (or deaths) in a given year to the population is called crude live birth (or crude death) rate for the year. However, this rate is influenced by the change in age structure of the population used as the denominator. For this reason, the standardized birth rate and the standardized death rate for Japanese population are calculated by the National Institute of Population and Social Security Research, by taking the population in 1930 as the standard population.
Standardized birth rate
First, the number of expected births in the standard population is obtained by applying the live (age-specific birth rates) in a given year to the standard population of women by age. Then the standardized birth rate for the year is calculated as the ratio of the above-mentioned number of births to the standard population.
Standardized death rate
First, the number of expected deaths in the standard population is obtained by applying the (age-sex-specific death rates) in a given year to the standard population by age and sex. Then the standardized death rate for the year is calculated as the ratio of the number of expected deaths to the standard population.
These rates, which indicate the fertility of a population in a given year, are obtained from age-specific birth rates of women. As to the Japanese women of the whole country, the following three kinds of reproduction rates are prepared annually by the National Institute of Population and Social Security Research.
Total fertility rate
The rate refers to the sum of the age-specific birth rates of women in the reproductive ages (from 15 to 49). It indicates the average number of children to be born to a woman who goes through her reproductive ages according to the age-specific birth rates of the year.
Gross reproduction rate
While the total fertility rate indicates the average number of children of both sexes born to a woman, the gross reproduction rate is limited to female live births only.
Net reproduction rate
The rate refers to the average number of surviving female live births to the child-bearing age, which is calculated from the age-specific female birth rate and the age-specific survival rate of women for a woman who bears children according to the age-specific female live birth rates through her reproductive ages. This rate indicates how much the female population is replaced during the period of one generation. A value exceeding 1 signifies that the female population will be increasingly reproduced in one generation, whereas a value smaller than 1 indicates decreasing replacement.
Life tables (Fundamental Statistics)
A life table expresses the mortality conditions of a population during a given period of time by means of age-sex-specific death rate, expectation of life, etc. The table is compiled on the basis of both the number of deaths observed during the period (reference period of the life table) and the population during the period or the mid-period population.
Two kinds of life tables, i.e., Complete Life Tables and Abridged Life Tables, are prepared by the Ministry of Health, Labour and Welfare. The former uses the precise results of the Population Censuses, while the latter are calculated in a simplified way using the annual Population Estimates. The Complete Life Tables have been published from the first issue for 1891 to 1898 through the twenty-first one for 2010.
Expectation of life
Expectation of life at a specified age is defined as the average years that a person is expected to live after reaching that age. The expectation of life at age 0 is often referred to as an average span of life.
Internal Migration in Japan Derived from the Basic Resident Registers
The Statistics Bureau, Ministry of Internal Affairs and Communications collects monthly such information as former address and sex of the in-migrants who were registered at the new address by notification or by the mayor's authority in conformity with Article 8 of the Residential Basic Book Act, and compiles statistics on the internal migration. It excludes those persons who moved within the boundary of a local municipality or whose previous addresses were unknown. The number also excludes persons whose period from out-migration to in-migration was one year or more. Though the records on foreigners became registered on the basic resident register network system due to the amendment of the Residential Basic Book Act, only the results on Japanese migrants are shown in this Yearbook.
The number of out-migrants is the number of persons who moved beyond the boundary of prefectures or municipalities (shi (cities), ku (wards), machi (towns) or mura (villages)). The figures of out-migrants are compiled by the former address (prefecture or municipality) by the Statistics Bureau.
Statistics on Legal Migrants
The statistics of international migration is compiled monthly and annually by the Ministry of Justice based on reports submitted by Regional Immigration Bureaus, their branches and sub-branches. Persons who legally entered or departed from Japan are those who completed due formalities under the Immigration-Control and Refugee-Recognition Act.