title: Challenges using online surveys in a Danish population of people with type 2 diabetes.
abstract: OBJECTIVE
  To investigate response rates for online and paper versions of an identical questionnaire and the differences between respondents to each and between respondents and non-respondents among a population with type 2 diabetes.
  
  
  METHODS
  We mailed letters containing an invitation to complete an online questionnaire to 2045 individuals, followed by two reminders; the second included a paper version of the questionnaire.
  
  
  RESULTS
  In total, 1081 people responded to either version of the questionnaire, yielding a response rate of 54%. Compared to total respondents, respondents completing the online version were more likely to be male, better educated, and younger, and have had diabetes for a shorter period of time. Compared to non-respondents, respondents were more likely to be male and have a lower hemoglobin A1c level.
  
  
  CONCLUSIONS
  Web-based surveys are capable of delivering a substantial number of responses cost-effectively. However, disadvantages related to selection bias should be taken into account, and mixed-mode methods should be considered when surveying populations with type 2 diabetes.
authors.affiliation: Steno Health Promotion Center, Steno Diabetes Center, Gentofte, Denmark.
authors.forename: Michaela
authors.initials: M
authors.lastname: Schiøtz
authors.forename: Mette
authors.initials: M
authors.lastname: Bøgelund
authors.forename: Ingrid
authors.initials: I
authors.lastname: Willaing
mesh_terms: D000328:Adult; D002908:Chronic Disease; D003718:Denmark; D003924:Diabetes Mellitus, Type 2 / Q000523:psychology / Q000628:therapy; D005260:Female; D019538:Health Care Surveys / Q000379:methods* / Q000592:standards; D006801:Humans; D020407:Internet; D016015:Logistic Models; D008297:Male; D015983:Selection Bias; D012648:Self Care; D011795:Surveys and Questionnaires / Q000592:standards