Within-person variability as a dynamic measure of late-life development: new methodologies and future directions.

BACKGROUND

Intra-individual variability is becoming a focus of research in behavioural gerontology due to theoretical and methodological advances.

OBJECTIVE

New directions in the study of intra-individual variability are described and unanswered questions are proposed.

METHODS

Papers from the special issue of Gerontology on Intra-individual Change are reviewed.

RESULTS

Key findings and approaches from this set of papers are identified, including types of latent growth curve models that incorporate dynamic elements and applications to the study of late-life cognition and affect. Theoretical issues that remain unresolved are outlined.

CONCLUSION

Dynamic approaches to the measurement of change provide novel methods to answer new questions and evaluate existing theories. The focus on intra-individual variability adds a valuable dimension to gerontological research that may refine the way we describe behaviour and measure change.