BASE-Publications:
Abstracts
Lindenberger, U., Gilberg, R., Nuthmann, R., Pötter, U.,
Little, T. D., & Baltes, P. B. (1999). Sample selectivity and
generalizability of the results of the Berlin Aging Study. In P. B. Baltes
& K. U. Mayer (Eds.), The Berlin Aging Study: Aging from 70 to 100
(pp. 56-82). Cambridge: Cambridge University Press.
In epidemiological investigations,
one common but rarely analyzed threat to generalizability is sample
selectivity, or nonrandom sample attrition. In this chapter, we describe our
approach to the study of selectivity, and provide in-depth analyses of the magnitude
of sample selectivity in the Berlin Aging Study. Of all individuals eligible
for participation (the verified parent sample, N = 1,908), 27% reached the
highest level of participation (the Intensive Protocol, N = 516). With respect
to levels of performance, projection of selectivity observed on lower levels of
participation onto Intensive Protocol constructs indicates that the Intensive
Protocol sample was, indeed, positively selected on medical, social, and
psychological dimensions. However, the magnitude of observed selectivity
effects did not exceed 0.5 standard deviations for any construct. In addition,
variances and covariance relations observed in the Intensive Protocol sample
were not markedly different from those found at lower levels of participation.
We conclude that the degree of selectivity in BASE fell within the usual range,
and did not result in a decrease of sample heterogeneity. Given the magnitude
of sample attrition and the high mean age of the sample, this is a satisfactory
result.