title: Mode of questionnaire administration can have serious effects on data quality.
abstract: BACKGROUND
  One of the main primary data collection instruments in social, health and epidemiological research is the survey questionnaire. Modes of data collection by questionnaire differ in several ways, including the method of contacting respondents, the medium of delivering the questionnaire to respondents, and the administration of the questions. These are likely to have different effects on the quality of the data collected.
  
  
  METHODS
  This paper is based on a narrative review of systematic and non-systematic searches of the literature on the effects of mode of questionnaire administration on data quality.
  
  
  RESULTS
  Within different modes of questionnaire administration, there were many documented potential, biasing influences on the responses obtained. These were greatest between different types of mode (e.g. self-administered versus interview modes), rather than within modes. It can be difficult to separate out the effects of the different influences, at different levels.
  
  
  CONCLUSIONS
  The biasing effects of mode of questionnaire administration has important implications for research methodology, the validity of the results of research, and for the soundness of public policy developed from evidence using questionnaire-based research. All users of questionnaires need to be aware of these potential effects on their data.
authors.affiliation: Department of Primary Care and Population Sciences, University College London, Hampstead Campus, Rowland Hill Street, London NW3 2PF, UK. a.bowling@pcps.ucl.ac.uk
authors.forename: Ann
authors.initials: A
authors.lastname: Bowling
mesh_terms: D015982:Bias; D003201:Computers; D006801:Humans; D007407:Interviews as Topic; D012919:Social Behavior; D011795:Surveys and Questionnaires; D013689:Telephone