Sample of the LASA data collection

The initial sample was weighted according to expected mortality at mid-term within each sex and age group, so that after five years equal numbers of men and women were expected to be alive in the ages 55-59, 60-64, 65-69, 70-74, 75-79, and 80-85 years. This design was expected to provide sufficient opportunity for multivariate research and for obtaining adequate subsamples for special studies. In addition, it should leave sufficient participants to be examined after a period of 10 years.

Municipal registries provided the sampling frame. The sample was constructed so as to reflect the national distribution of urbanization and population density. The sample was based in three culturally distinct geographical areas in the West, North-East, and South of the Netherlands. Each area consists of one middle- to large-size city and two or more rural municipalities which border on the city. The municipalities included in the sample are: Amsterdam, Wormerland, Waterland (three municipalities in the West), Zwolle, Ommen, Genemuiden, Zwartsluis, Hasselt (North-East), and Oss, Uden, Boekel (South). Within follow-up observations, subjects who moved out of the municipality were traced and re-interviewed.

LASA uses the sample of the NESTOR-program "Living arrangements and social networks of older adults" (LSN). This is essentially a cross-sectional study, with follow-up of specific smaller subsamples. While LASA is designed as an interdisciplinary project with potentially policy relevant outcomes, the main purpose of LSN is the development of theory and methods for the study of living arrangements and social networks in old age.

To be able to distinguish age, cohort and period effects, in 2002 a new cohort (birth years 1938-1947) has been sampled from the same sampling frame as the original cohort.

Composition of the realized sample (number of respondents) with respect to year of birth