Suchergebnisse

A focus on the study of development and other kinds of changes in the whole individual has been one of the hallmarks of research by Magnusson and his colleagues. A number of different approaches emphasize this individual focus in their respective ways. This presentation focuses on intraindividual variability stemming from Cattell's P-technique factor analytic proposals, making several refinements to make it more tractable from a research design standpoint and more appropriate from a statistical analysis perspective. The associated methods make it possible to study intraindividual variability both within and between individuals. An empirical example is used to illustrate the procedure.

Examines the contribution of the concepts of stability & intraindividual variability to the study of adult development. Stability is understood as a class of concepts that refer to consistency in structural, normative, ipsative, & level invariances in the aging process. Similarly, intraindividual variability is defined as a class of concepts referring to within-person changes. During the 20th century, perspectives on aging stressing stability have predominated. However, in the past few decades, it has come to be recognized that life involves cycles, oscillations, & fluctuations that involve both stability & change. Though this process appears to be relatively uniform, in fact, it is built on a substrate of intraindividual variability. Thus, aging has come to be understood within a frame of intraindividual variability rather than of putative stability. This new perspective has begun to alter all aspects of research on the aging process. D. Ryfe

A new genetic factor model for multivariate phenotypic time series, iFACE, is presented which allows for the estimation of subject-specific model parameters of genetic and environmental factors. The iFACE was applied to multivariate EEG registrations obtained with single dizygotic twin pairs. The results showed evidence for considerable subject-specificity in heritabilities and environmental effects. The assumption that the population is homogeneous (i.e., that each case in the population obeys the same parametric model), does not hold for these psychophysiological data, and its use should be critically reconsidered. We conclude that the iFACE provides a powerful new methodology to assess heterogeneity (subject-specificity) based on phenotypic observations.