2015-2040年日本家庭人口预测（英）

Household Projections for Japan 2015-2040 1) Outline of Results and Methods Introduction “Household Projections for Japan (Outline of Results and Methods)” projected the number of households nationwide and was released in 2018. The initial population used as the benchmark of the projections was obtained by adjusting the results of the 2015 Census. I. Framework of Projections 1. Period of Projections The period for the present projections is the twenty-five years from October 1, 2015 to October 1, 2040. 2. Method and Results of Projections The essential part of the household projections was carried out by the household transition method. This method projects distributions by combination of future marital states and household positions, by setting transition probabilities of members private households, and applies them to the population by sex and five-year age group of “Population Projections for Japan (Published in 2017)” 2) (medium fertility/medium mortality variant) in order to project the population by sex, five-year age group, and combination of marital state and household positions. Households are identified with markers such as “one-person households,” “couple-only households,” “couple-and-child(ren) households,” “one-parent-and-child(ren) households,” and “other households.” Markers refer to members regarded as key persons in terms of household formation/dissolution in projection models and usually match with the household heads of the Census. For exceptional cases such as a wife or a child becoming the head of “couple-and-child(ren) households,” we set certain rules such as the marker of “couple-and-child(ren) households” always being the husband and the marker of “one-parent-and-child(ren) households” always being the parent. We applied the correspondence between head/non-head and marker/non-marker in 2015 to the projected population by sex, by five-year age group, and by marital state and household positions (marker/ non-marker) to obtain the number of heads by sex, five-year age group, marital state, and family type. The detailed results of the projections are shown in Result Table 1 (Number of Private Households by Family Type, Mean Household Members, Mean Size of Households) and Result Table 2 (Number and Percentages of Private Households by Head's Sex and Five-year Age Group, by Family Type). 3. Initial Population We obtained the initial population used as the benchmark of the projections based on the 2015 Census, by converting positions of members within private households from heads/non-heads by family type to markers/non-markers by family type. 4. Variants of Projections The present projections handle only one case. Additionally, for reference, we also calculated the number of households under the assumption that the distributions by sex, five-year age group, and combination of marital state and household positions remain constant from 2015 and onward. 1 The purpose of the projections is to obtain a future n