Experiences from longitudinal studies of aging: An international perspective.

A review of current longitudinal studies of aging was undertaken to obtain background information for the initiation of new studies. Through interviews with investigators information was obtained on the aspects of population and sampling, topic selection, data collection, data quality, and collaboration. All investigators emphasized the importance of broad, multidisciplinary data collection to meet future research interests. Differences between studies are mainly related to organization, sampling design, and monitoring of data quality.