title: What makes a good staging algorithm: examples from regular exercise.
abstract: OBJECTIVE
  This study retrospectively compared subjects from three unrelated studies using eight algorithms to stage exercise behavior.
  
  
  METHODS
  Study One included 936 employees involved in a smoking cessation study at four worksites--a medical center, retail store, manufacturing firm, and a government agency. Study Two included 19,212 members of a New England HMO; and Study Three included a convenience sample of 327 adult New Englanders.
  
  
  METHODS
  The eight algorithms used different descriptions of stages based on the transtheoretical model, as well as different definitions of exercise and response formats.
  
  
  RESULTS
  Algorithms using longer, more precise definitions of exercise resulted in larger numbers of subjects being staged in precontemplation and contemplation in comparison to algorithms using shorter definitions, which tended to stage subjects in preparation and action. Maintenance was the most and preparation the least consistently described stage across algorithms.
  
  
  CONCLUSIONS
  Alteration of the descriptions of stage and the definition of exercise has consequences for the staging of subjects. Definitions need to be explicit, stating all parameters needed to meet criterion, and subjects must be able to assess themselves. Either a 5-Choice or a true/false response format is effective in assessing stage.
authors.affiliation: Center for Health Behavior Research, Washington University School of Medicine, St. Louis, Missouri 63108, USA. greed@im.wustl.edu
authors.forename: G R
authors.initials: GR
authors.lastname: Reed
authors.forename: W F
authors.initials: WF
authors.lastname: Velicer
authors.forename: J O
authors.initials: JO
authors.lastname: Prochaska
authors.forename: J S
authors.initials: JS
authors.lastname: Rossi
authors.forename: B H
authors.initials: BH
authors.lastname: Marcus
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015444:Exercise; D005260:Female; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009511:New England; D011594:Psychometrics; D012189:Retrospective Studies