A Generation Life Table for the People Born in 1891

Abstract

The first life table in Japan was constructed by using the data for l891-98. Since then seven complete life tables were constructed at irregular intervals; and since 1949 abridged life tables were published annually.
By using these life tables a generation life table was computed by the following procedure:
It was assumed that 100, 000 babies were born simultaneously at the beginning of 1891 and exposed to the infant mortality (q₀) shown in the first life table; when they became one year old in the next calendar year, they were exposed to q₁ in that life table, and so on : When they became 8 years old in 1899 they were exposed to q₈ in the second life table for 1899-1903, and so on.
For the blank calendar years for which no life tables were constructed, the mortality rates required were estimated by weighted means derived from tables for preceding and following calendar years, more emphasis being laid on the nearer one.
By this procedure l_x, d_x, q_x, p_x could be computed till the age 65. As there are a considerable number of persons who were born in 1891 and have attained the age 65 this year (1956) still living today, e_x can not be computed. But if it is assumed that the persons 65 years old today would have the same expectation of life in the future as e₆5 shown in 1955 life table (this assumption seems not very absurd), then e_x of the generation life table for the people born in 1891 can be computed. This assumption was adopted in this life table.
The result is shown in Table and Graphs in the text.