Starting in 1975, each respondent was contacted by phone approximately every two years, then again in person one year after the second phone interview. This pattern continued until 1988. Starting in 1991, respondents were interviewed personally biennially. The survey began using computer-aided personal interviews in 1995. Dependent interviewing For each interview, there is an extensive preload of household, employment, and personal information that was gathered in previous interviews.
Some information is collected in an event history format.
Processing - Family composition editing.