title: Creating case scenarios or vignettes using factorial study design methods.
abstract: OBJECTIVE
  This paper is a report of a study conducted to develop clinical case vignettes using an adaptation of an incomplete factorial study design methodology.
  
  
  BACKGROUND
  In health care, vignettes or cases scenarios are core to problem-based learning, common in practice guideline development processes, and increasingly being used in patient or care-giver studies of chronic or life-threatening illnesses. A large number of behavioural, psycho-social and clinical factors can be relevant in such decision problems. Unbiased methods for choosing what factors to include are needed, when it is not possible to include all relevant combinations of factors in the vignettes.
  
  
  METHODS
  The factors to be considered, number of levels or categories for each factor, and desired number of scenarios were decided in advance. An algorithm was used first to create the full factorial data set, and then a random subset of combinations was generated, according to predefined criteria, based on maximizing determinants. The subset of combinations was incorporated into written vignettes. The study was conducted in 2004-2005.
  
  
  RESULTS
  Application of the method yielded diverse and balanced scenarios that covered the full range of factors to be considered for a project to elicit health providers' processes in diet counselling for dyslipidemia.
  
  
  CONCLUSIONS
  The approach is flexible, decreases possible researcher bias in the creation of vignettes, and can improve statistical power in survey research. This novel application of study design methodology merits consideration when vignettes are being developed to elicit opinions or decisions in studies of complex health issues.
authors.affiliation: Department of Family Relations & Applied Nutrition, University of Guelph, Canada. pbrauer@uoguelph.ca
authors.forename: Paula M
authors.initials: PM
authors.lastname: Brauer
authors.forename: Rhona M
authors.initials: RM
authors.lastname: Hanning
authors.forename: Jose F
authors.initials: JF
authors.lastname: Arocha
authors.forename: Dawna
authors.initials: D
authors.lastname: Royall
authors.forename: Richard
authors.initials: R
authors.lastname: Goy
authors.forename: Andrew
authors.initials: A
authors.lastname: Grant
authors.forename: Linda
authors.initials: L
authors.lastname: Dietrich
authors.forename: Roselle
authors.initials: R
authors.lastname: Martino
authors.forename: Julie
authors.initials: J
authors.lastname: Horrocks
mesh_terms: D003657:Decision Making; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D010865:Pilot Projects; D018794:Problem-Based Learning / Q000379:methods*; D012107:Research Design