A: Although both of them are the same in the point of life tables that express mortality as a function of age, there are following differences.
The life tables in the Japanese Mortality Database are consistent with the Human Mortality Database, which is an international mortality database, and are optimized and comprehensively reorganized for mortality research. The official life table is a life table that represents the latest mortality situation in Japan as official statistics.
For this reason, the Japanese Mortality Database adopts a uniform format and estimation method, and the figures are sometimes revised retrospectively due to the development of the methods. Due to these differences in objectives and methods, life expectancy of the two show roughly the same trends, but not exactly the same.
Please be aware of these points when using this database.

A: The Japanese Mortality Database provides life tables optimized for mortality research. The mortality data provided in this database has been processed beforehand, for example, through unknown proportional divisions, etc. in order to create a mortality table; hence, it is not in raw data form. More information about the raw data can be obtained from "Vital Statistics" from the Ministry of Health, Labor and Welfare.

A: When a new methodology is developed and/or a new way of using statistical information is found, the Japanese Mortality Database may go back and update some of its old data. Therefore, we recommend that you keep a record of the download date, in case you need to use it when presenting research results. Also, please refer to the "Citation Guidelines" for more information on citations.