title: Words or graphics to present a Discrete Choice Experiment: Does it matter?
abstract: OBJECTIVE
  To test whether presenting attribute levels in words or graphics generates different results with respect to attribute level interpretation, relative importance and participation probabilities.
  
  
  METHODS
  Parents of 959 newborns completed a DCE questionnaire that contained two versions of the same nine choice tasks in which the attribute levels were presented in words or graphics. Five attributes related to the decision of parents to vaccinate their newborn against rotavirus were included. Mixed-logit models were conducted to estimate the relative importance of the attribute levels.
  
  
  RESULTS
  Respondents who started with the choice tasks in words produced the most consistent answer patterns. All respondents significantly preferred words to graphics. Part-worth utilities and the relative importance of the attribute levels differed based on the words and graphics data, resulting in different probabilities to participate in vaccination.
  
  
  CONCLUSIONS
  Words were preferred over graphics, resulted in higher choice consistency, and showed more valid attribute level estimates. Graphics did not improve respondents' understanding of the attribute levels.
  
  
  CONCLUSIONS
  Future research on the use of either words or graphics is recommended in order to establish guidelines on how to develop a valid presentation method for attribute levels in the choice tasks of a DCE.
authors.affiliation: Centre for Nutrition, Prevention and Health Services, National Institute for Public Health and the Environment, Bilthoven, The Netherlands; Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands. Electronic address: Jorien.Veldwijk@rivm.nl.
authors.forename: Jorien
authors.initials: J
authors.lastname: Veldwijk
authors.affiliation: Centre for Nutrition, Prevention and Health Services, National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
authors.forename: Mattijs S
authors.initials: MS
authors.lastname: Lambooij
authors.affiliation: Health Technology and Services Research, University of Twente, Enschede, The Netherlands.
authors.forename: Janine A
authors.initials: JA
authors.lastname: van Til
authors.affiliation: Health Technology and Services Research, University of Twente, Enschede, The Netherlands.
authors.forename: Catharina G M
authors.initials: CG
authors.lastname: Groothuis-Oudshoorn
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Henriëtte A
authors.initials: HA
authors.lastname: Smit
authors.affiliation: Centre for Nutrition, Prevention and Health Services, National Institute for Public Health and the Environment, Bilthoven, The Netherlands; Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: G Ardine
authors.initials: GA
authors.lastname: de Wit
mesh_terms: D002755:Choice Behavior; D003142:Communication; D003196:Computer Graphics; D004522:Educational Status; D005260:Female; D057220:Health Literacy; D006801:Humans; D016015:Logistic Models; D008297:Male; D012107:Research Design; D011795:Surveys and Questionnaires
keywords: Attributes; Conjoint analysis; Discrete choice experiment; Framing; Graphics; Icons