title: Maximising responses to discrete choice experiments: a randomised trial.
abstract: OBJECTIVE
  To identify any differences in response and completion rates across two versions of a questionnaire, in order to determine the trade-off between a potentially higher response rate (from a short questionnaire) and a greater level of information from each respondent (from a long questionnaire).
  
  
  METHODS
  This was a randomised trial to determine whether response rates and/or results differ between questionnaires containing different numbers of choices: a short version capable of estimating main effects only and a longer version capable of estimating two-way interactions, provided certain assumptions hold. Best-worst scaling was the form of discrete choice experimentation used. Data were collected by post and analysed in terms of response rates, completion rates and differences in mean utilities.
  
  
  RESULTS
  Fifty-three percent of individuals approached agreed to take part. From these, the response to the long questionnaire was 83.2% and the short questionnaire was 85.1% (difference 1.9%, 95% CI -7.3, 11.2; p = 0.68). The two versions of the questionnaire provided similar inferences.
  
  
  CONCLUSIONS
  This trial indicates that, in a healthcare setting, for this complexity of questionnaire (i.e. four attributes and the best-worst scaling design), the use of 16 scenarios obtained very similar response rates to those obtained using half this number.
authors.affiliation: Health Economics Facility, Health Services Management Centre, University of Birmingham, Birmingham, UK. j.coast@bham.ac.uk
authors.forename: Joanna
authors.initials: J
authors.lastname: Coast
authors.forename: Terry N
authors.initials: TN
authors.lastname: Flynn
authors.forename: Chris
authors.initials: C
authors.lastname: Salisbury
authors.forename: Jordan
authors.initials: J
authors.lastname: Louviere
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Peters
mesh_terms: D002755:Choice Behavior; D006801:Humans; D012107:Research Design; D011795:Surveys and Questionnaires