GENDER - Population
Population comprises unlike-sex twin pairs born between 1906 and 1925 (Gold et al., 2002). A survey concerning health and health behavior was mailed in 1994 with responses from 1210 twins from 605 pairs where both responded. Mean age at baseline questionnaire assessment was 74.43 (SD 4.28) and all were Caucasians. A baseline in-person evaluation of 498 twins from 249 pairs between 70 and 80 years of age was undertaken between 1995 and 1997, and included an interview and tests of cognitive and physical functioning. Two additional in-person waves followed at 4-year intervals. Finally, a second survey was mailed in 2007 to all living twins who participated in the first mailed survey.
Data Collection Event
GENDER - Baseline survey
Baseline survey consisted of questions pertaining to health status and health-related behaviors and attitudes, as well as demographics and psychosocial factors such as social support. .