Japan 1900–2010, population 25 years and older
In 1900, only 4.9% of the Japanese population older than 25 years had received at least lower secondary education. This proportion increased to 52.3% until 1950 and to 96.2% until 2010. By then, about 34.5% of the population aged 25 years or older finished a post-secondary education while 3.8% had primary education or less as their highest educational attainment. Mean years of schooling of the population 25 years or older increased from 2.0 years in 1900 to 6.7 years in 1950 and to 11.3 years in 2010.
In Japan, gender differences in educational attainment have been more or less diminished during the 20th century. In 1900, 5.8% of the men aged 25 years and older had at least lower secondary education, compared to about 3.9% of the women. By 1950 about 65.7% of the men and 70.5% of the women aged 30 to 34 years had achieved at least lower secondary education while for instance this share was only 21.1% and 23.9% for the population aged 65–69. Completed lower secondary education became universal for men (93.3%) and women (92.7%) by 1975. Since 2000, there has been an inverse gender gap in higher education, with larger proportions of women completing post-secondary education than men. In 2010, about 60.5% of women in the 30–34 age group had post-secondary educational attainment, compared to 52.9% of men.
The EDU20C estimates of the population of Japan by age, sex and education are based on several census datasets dating back to 1898. Japanese censuses provide information on highest educational attainment in decennial intervals for the time since 1960.Before that there are no data on education or literacy by age and sex available. For Japan in the period 1950 to 2010 we have only 5 educational categories as incomplete and complete primary education cannot be disaggregated and are merged in the category primary education.
In the first historic census data covering information on education attainment data reliability issues arises from the different educational categorization compared to the current education system. For Japan it was necessary to extend the open-ended age group (95+ years) existing life tables by using a logistic extrapolation of nqx, Lx and ax to get life tables up to the open-ended age group 100+ years. Additionally it was necessary to generate life tables for missing data-points by interpolating/extrapolating life expectancies at birth by sex. The model fits a logistic function to existing life expectancies at birth, given the values of upper and lower asymptotes. Based on these estimated life expectancies we use a function that interpolates the logarithms of the probabilities of dying (nqx) from two life tables to generate a comprehensive set of life tables for the entire reconstruction period. Both R functions are in their methodological core based on the Population Analysis System (PAS) Excel templates E0LGST and INTPLTF/INTPLTM. Additionally, some historical source data on the population structure were only available for insufficient large open-ended age groups (e.g. 75+ years from 1900 to 1950), what required an age structure extension to 100+ years based on Lx information from the life tables. Furthermore, it was necessary to interpolate the intercensal data-points for population by age and sex using a linear interpolation function.
For Japan the major source of data on population by age, sex and educational attainment in the 20th century originates from the Japanese National Statistical Bureau. For the EDU20C reconstruction, we also used information on mortality extracted from the life tables available in the Human Life-table Database (HLD) and the Human Mortality Database (HMD).