title: Within-person variability as a dynamic measure of late-life development: new methodologies and future directions.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Ageing Research Unit, Centre for Mental Health Research, Australian National University, Canberra, Australia. kaarin.anstey@anu.edu
authors.forename: Kaarin J
authors.initials: KJ
authors.lastname: Anstey
mesh_terms: D000367:Age Factors; D000375:Aging / Q000502:physiology* / Q000523:psychology; D003071:Cognition / Q000502:physiology*; D005853:Geriatrics / Q000379:methods* / Q000592:standards; D006803:Human Development / Q000502:physiology*; D006801:Humans; D012307:Risk Factors; D013997:Time Factors