Last Revised: January 30, 2007
BRIEF SUMMARY of the Methods Protocol for the Human Mortality Database
R. Wilmoth, K. Andreev, D. Jdanov, and D.A. Glei with the assistance of
Boe, M. Bubenheim, D. Philipov, V. Shkolnikov, P. Vachon1
The Human Mortality Database (HMD) contains uniform death rates and life tables (e.g., life expectancy) for various populations. It also includes the original raw data (i.e., births, deaths, census counts or official population estimates) from which they were derived. The following comprises a brief summary of the methodology used to calculate the HMD life tables. For a complete description, see the full Methods Protocol available at:
For more information about the format of HMD data files, see the explanation given at: www.mortality.org/Public/DataFilesExplanation.html
Steps for computing mortality rates and life tables
There are six steps involved in computing mortality rates and life tables for the HMD. Here is an overview of the process:
1. Births. Annual counts of live births by sex are collected for each population over the longest time period available. At a minimum, a complete series of birth counts is needed for the time period over which mortality rates and period life tables are computed. These counts are used mainly for estimating the size of individual cohorts (on January 1st of each year) from their birth until the next census, and for other adjustments based on relative cohort size.
2. Deaths. Death counts are collected by sex, completed age, year of birth, and year of death if available. The raw death counts for a given calendar year may be available by completed age (or age group) but not by year of birth. Before making subsequent calculations, deaths of unknown age may be distributed proportionately across the age range, and aggregated deaths are split into finer age categories. 2
3. Population size. Below age 80, estimates of population size on January 1st of each year are either obtained from another source (most commonly, official estimates) or derived using intercensal survival3 as depicted in Figure 1 (shown in red). In most cases, all available census counts are collected for the time period over which mortality rates and life tables are computed. The maximum level of age detail available in the raw data is always retained and used in subsequent calculations. When necessary, persons of unknown age are distributed proportionately across age before making subsequent calculations such as intercensal population estimation and calculation of mortality rates. Above age 80, population estimates
1 This document is the direct result of a series of discussions held in Rostock, Germany, and Berkeley, U.S.A., beginning in June 2000. The individuals on this list not only participated in those discussions but also made important contributions to the set of methods described here. All graphs in the main text were drawn by Georg Heilmann.
2 For more details regarding the methods for redistributing deaths of unknown age and splitting aggregated deaths into finer age categories, see pp. 10-15 of the Methods Protocol.
For details about the method of intercensal survival, see pp. 16-27 of the Methods Protocol.