title: Dealing with short-term fluctuation in longitudinal research.
abstract: OBJECTIVE
  Many analytical methods are not very sensitive to change because of the difficulty of distinguishing short-term fluctuation from the developmental change of primary interest. The current project investigated one possible solution to this problem in the form of a measurement-burst design in which research participants perform several versions of each test at each measurement occasion.
  
  
  METHODS
  Over 1,200 adults across a wide-age range performed different versions of cognitive tests on several sessions at each measurement occasion.
  
  
  RESULTS
  Four methods of incorporating short-term variability were compared with respect to the magnitude of the correlations of the ability measures with each other and with respect to the magnitude of their relations with age.
  
  
  CONCLUSIONS
  The results revealed that more sensitive assessments of change can be obtained by taking short-term fluctuation into account with measurement-burst designs. In particular, capitalizing on the availability of multiple measures at each occasion to form latent constructs representing the level and change in cognitive performance may provide the most sensitive assessment of cognitive change.
authors: Department of Psychology, University of Virginia, Charlottesville, VA 22904, USA. salthouse@virginia.edu
authors: Timothy A
authors: TA
authors: Salthouse
authors: John R
authors: JR
authors: Nesselroade
mesh_terms: D000367:Age Factors; D000375:Aging / Q000523:psychology; D003071:Cognition / Q000502:physiology; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity; D013997:Time Factors