title: Selectivity of attrition in longitudinal studies of cognitive functioning.
abstract: OBJECTIVE
  Identify characteristics distinguishing people who do and do not continue to participate in a longitudinal study and determine whether the longitudinal changes for people who continue are representative of the changes that would have occurred had longitudinal data been available from all of the initial participants.
  
  
  METHODS
  Moderately large samples of returning (N = 2,082) and nonreturning (N = 1,698) participants across a wide age range (i.e., 18-97 years of age) performed a battery of cognitive tests and completed personality and mood questionnaires. Differences between the groups were examined with multiple regression analyses with age, returner status, and their interaction as predictors.
  
  
  RESULTS
  Compared with participants who did not return, returning participants at the initial occasion had higher levels of each cognitive ability and of certain personality characteristics (e.g., agreeableness and openness), but many of the differences were only apparent among adults older than 50 years of age. Importantly, there was no evidence that the longitudinal change for nonreturning participants would have been different from that among the participants who did return.
  
  
  CONCLUSIONS
  The phenomenon of selective attrition is more complex than often assumed, and it may not necessarily limit the generalizability of longitudinal comparisons.
authors.affiliation: Department of Psychology, University of Virginia, Charlottesville. salthouse@virginia.edu.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Salthouse
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition / Q000502:physiology*; D003627:Data Interpretation, Statistical; D006801:Humans; D008137:Longitudinal Studies / Q000592:standards* / Q000706:statistics & numerical data; D008875:Middle Aged; D010352:Patient Dropouts / Q000523:psychology / Q000706:statistics & numerical data; D010551:Personality / Q000502:physiology*; D012107:Research Design / Q000592:standards* / Q000706:statistics & numerical data; D055815:Young Adult
keywords: Attrition; Cognitive change; Longitudinal.