A systemic-wholistic view of psychological functioning in very old age: introduction to a collection of articles from the Berlin Aging Study.

Introduced are articles from the Berlin Aging Study (BASE) that collectively illustrate systemic-wholistic approaches to psychological functioning in old age. A systemic-wholistic perspective aims to elucidate structural and functional interdependencies between domains and to provide an integrative account of individual functioning. The special features of BASE (age range, 70-105 years; heterogeneous sample stratified by age and gender; and multidisciplinary data collection) are suited to this purpose. This article outlines the design of BASE, describes the cross-sectional sample (N = 516: 258 men and 258 women), and reports sample selectivity analyses on 25 criterion variables in which the Pearson-Lawley selection formulas were used. Although the BASE sample is positively biased, it is not restricted in heterogeneity and does not exhibit major differences in patterns of covariation among variables. This finding supports the use of BASE data for the intended systemic-wholistic analyses.