For individuals born in Ohio and North Carolina from 1900 to 1930 (generation 2), LIFE-M's variables include:
- birth family characteristics (e.g., birth order, sibling sex composition, age differences, twinning, number of siblings);
- health (date and place of death, i.e. longevity);
- parental and grandparent characteristics (e.g., age, race, occupation, education, and birth state or country from the censuses);
- own economic and demographic outcomes (wages, employment, occupation, birth state or country, education from the 1940 census);
- marriage family characteristics (e.g., age at marriage, spouse and characteristics including all characteristics on this list);
- own births (number of children, mortality of own infants and children, timing of births, sex composition, and twinning); and
- geographic location (town or address) at vital events and census enumeration (lifetime mobility).
LIFE-M's Sample Sizes
LIFE-M includes very large samples of Americans relative to other available historical data, especially for women and under-represented minorities.
Women can be linked, because vital records typically contain information on women's birth and married names. Census linking projects based on surnames necessarily exclude women who change their names at marriage. Birth certificates contain information on mothers' birth names in the majority of cases. While coverage is incomplete, marriage certificates contain information on the birth names of the bride and groom. This information provides a cross-walk between women's names that facilitates the inclusion of this group. Although many historical longitudinal samples exclude women by necessity (e.g. the Union Army veterans) or because they cannot be linked by last name (Census-Census linking), LIFE-M will follow large, representative samples of women longitudinally and across generations.