title: Agreement between web-based and paper versions of a socio-demographic questionnaire in the NutriNet-Santé study.
abstract: OBJECTIVE
  Web-based studies nowadays raise a major interest as they can improve all steps involved in observational studies. Our objective was to compare the web-based version of the NutriNet-Santé self-administered socio-demographic and economic questionnaire with the traditional paper version.
  
  
  METHODS
  Both versions of the questionnaire were sent to 170 volunteers and filled in by 147 of them (either paper first, n = 76, or web-based first, n = 71). Agreement between versions was assessed by intraclass correlations (ICC) and kappas.
  
  
  RESULTS
  Agreement between both versions was high, with ICC and kappas ranging between 0.81-1.00 and 0.76-1.00, respectively, similarly across groups of administration order, age, gender and self-estimated web knowledge in general. The web-based version was the one preferred by 93.7% of the subjects and enabled to avoid 553 missing values (2.00% of the total entries), 24 inconsistent data (0.09%), 8 aberrant data (0.03%), 472 data entry errors (0.85%) and to save 2,800 <euro> (US $4,072) when sent to 170 subjects.
  
  
  CONCLUSIONS
  The web-based socio-demographic and economic questionnaire provided information of similar-to-superior quality compared to the traditional paper version, with substantial logistic and cost advantages.
authors.affiliation: Unité de Recherche en Epidémiologie Nutritionnelle (UREN), Bobigny Cedex, France.
authors.forename: Anne-Claire
authors.initials: AC
authors.lastname: Vergnaud
authors.forename: Mathilde
authors.initials: M
authors.lastname: Touvier
authors.forename: Caroline
authors.initials: C
authors.lastname: Méjean
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Kesse-Guyot
authors.forename: Clothilde
authors.initials: C
authors.lastname: Pollet
authors.forename: Aurélie
authors.initials: A
authors.lastname: Malon
authors.forename: Katia
authors.initials: K
authors.lastname: Castetbon
authors.forename: Serge
authors.initials: S
authors.lastname: Hercberg
mesh_terms: D000368:Aged; D005260:Female; D006306:Health Surveys / Q000379:methods*; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires