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Intercensal Adjustment of Current Population Estimates (2015 - 2020)
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I Method of Intercensal Adjustment of Current Population Estimates
The intercensal adjusted population
The population estimates as of the first day of each month are calculated using the recent census population. However, the estimated population as of October 1, 2020 based on the Census population of 2015 is not necessarily equal to the Census population of 2020. Therefore, the population estimates between the 2015 and the 2020 Population Censuses have been revised by the intercensal adjustment.
The intercensal adjustment was made for the following population.
(1) The population by sex and age for Japan as of the first day of each month (November 2015 to September 2020)
(2) The population by sex and age for prefectures as of October 1 of each year (2016 to 2019)
Outline of intercensal adjustment
1 Intercensal adjusted population as of October 1 of each year by prefectures
(1) Method of calculationIntercensal adjusted population of the stated year
= Total intercensal adjusted population by age of the stated year
Intercensal adjusted population by age of the stated year
= Intercensal adjusted population by age of the previous year
+ Total net change by age from October of the previous year to September of the stated year
+ Intercensal adjustment value by age
(2) Intercensal adjusted population of the previous year (Base population)
The complete counts of Census population are used as the base population for the year following a Population Census, and for the year after the following year and thereafter, the final population estimates as of October 1 of the previous year is used as the base population.
As for October 1, 2015, it is the Census population of 2015 (included unknown age population after being prorated).
(3) Total net change (from October of the previous year to September of the stated year)
| Total net change | = Natural change |
| + Migration change + Net increase by change of nationality (for Japanese population only) |
The difference between the estimated population as of October 1, 2020 based on the complete counts of 2015 Population Census and the complete counts of 2020 Population Census is divided and applied to the estimate by age of each year.
2 Intercensal adjusted population as of the first day of each month, Japan
(1) Method of calculationIntercensal adjusted population of the stated month
= Total intercensal adjusted population by age (five-year group) of the stated month
Intercensal adjusted population by age (five-year group) of the stated month
= Intercensal adjusted population by age (five-year group) of the previous month
+ Total net change by age (five-year group) of the previous month
+ Intercensal adjustment value by age (five-year group)
(2) Intercensal adjusted population of the previous month (Base population)
The complete counts of Census population are used as the base population for the month following a Population Census, and for the month after the following month and thereafter, the final population estimate as of the first day of the previous month is used.
As for October 1, 2015, it is the Census population of 2015 (included unknown age population after being prorated).
(3) Total net change (from the first day to the last day of the previous month)
| Total net change | = Natural change |
| + Migration change + Net increase by change of nationality (for Japanese population only) |
The difference between the estimated population as of October 1, 2020 based on the complete counts of 2015 Population Census and the complete counts of 2020 Population Census is divided and applied to the estimate by age (five-year group) of each month.
