title: Reliability and validity of three questionnaires measuring context-specific sedentary behaviour and associated correlates in adolescents, adults and older adults.
abstract: BACKGROUND
  Reliable and valid measures of total sedentary time, context-specific sedentary behaviour (SB) and its potential correlates are useful for the development of future interventions. The purpose was to examine test-retest reliability and criterion validity of three newly developed questionnaires on total sedentary time, context-specific SB and its potential correlates in adolescents, adults and older adults.
  
  
  METHODS
  Reliability and validity was tested in six different samples of Flemish (Belgium) residents. For the reliability study, 20 adolescents, 22 adults and 20 older adults filled out the age-specific SB questionnaire twice. Test-retest reliability was analysed using Kappa coefficients, Intraclass Correlation Coefficients and/or percentage agreement, separately for the three age groups. For the validity study, data were retrieved from 62 adolescents, 33 adults and 33 older adults, with activPAL™ as criterion measure. Spearman correlations and Bland-Altman plots (or non-parametric approach) were used to analyse criterion validity, separately for the three age groups and for weekday, weekend day and average day.
  
  
  RESULTS
  The test-retest reliability for self-reported total sedentary time indicated following values: ICC = 0.37-0.67 in adolescents; ICC = 0.73-0.77 in adults; ICC = 0.68-0.80 in older adults. Item-specific reliability results (e.g. context-specific SB and its potential correlates) showed good-to-excellent reliability in 67.94%, 68.90% and 66.38% of the items in adolescents, adults and older adults respectively. All items belonging to sedentary-related equipment and simultaneous SB showed good reliability. The sections of the questionnaire with lowest reliability were: context-specific SB (adolescents), potential correlates of computer use (adults) and potential correlates of motorized transport (older adults). Spearman correlations between self-reported total sedentary time and the activPAL™ were different for each age group: ρ = 0.02-0.42 (adolescents), ρ = 0.06-0.52 (adults), ρ = 0.38-0.50 (older adults). Participants over-reported total sedentary time (except for weekend day in older adults) compared to the activPAL™, for weekday, weekend day and average day respectively by +57.05%, +46.29%, +53.34% in adolescents; +40.40%, +19.15%, +32.89% in adults; +10.10%, -6.24%, +4.11% in older adults.
  
  
  CONCLUSIONS
  The questionnaires showed acceptable test-retest reliability and criterion validity. However, over-reporting of total SB was noticeable in adolescents and adults. Nevertheless, these questionnaires will be useful in getting context-specific information on SB.
authors.affiliation: Department Movement and Sport Sciences, Ghent University, Watersportlaan 2, B-9000, Ghent, Belgium. Cedric.Busschaert@UGent.be.|Fund for Scientific Research Flanders (FWO), Egmontstraat 5, 1000, Brussels, Belgium. Cedric.Busschaert@UGent.be.
authors.forename: Cedric
authors.initials: C
authors.lastname: Busschaert
authors.affiliation: Department Movement and Sport Sciences, Ghent University, Watersportlaan 2, B-9000, Ghent, Belgium. Ilse.Debourdeaudhuij@UGent.be.
authors.forename: Ilse
authors.initials: I
authors.lastname: De Bourdeaudhuij
authors.affiliation: Department Movement and Sport Sciences, Ghent University, Watersportlaan 2, B-9000, Ghent, Belgium. Veerle.vanholle@ugent.be.|Fund for Scientific Research Flanders (FWO), Egmontstraat 5, 1000, Brussels, Belgium. Veerle.vanholle@ugent.be.
authors.forename: Veerle
authors.initials: V
authors.lastname: Van Holle
authors.affiliation: School of Health and Life Science, Institute of Applied Health Research, Glasgow Caledonian University, Cowcaddens Road, Glasgow, G4 0BA, Scotland, UK. Sebastien.Chastin@gcu.ac.uk.
authors.forename: Sebastien F M
authors.initials: SF
authors.lastname: Chastin
authors.affiliation: Department Movement and Sport Sciences, Ghent University, Watersportlaan 2, B-9000, Ghent, Belgium. greet.cardon@ugent.be.
authors.forename: Greet
authors.initials: G
authors.lastname: Cardon
authors.affiliation: Department Movement and Sport Sciences, Ghent University, Watersportlaan 2, B-9000, Ghent, Belgium. katrien.decocker@ugent.be.|Fund for Scientific Research Flanders (FWO), Egmontstraat 5, 1000, Brussels, Belgium. katrien.decocker@ugent.be.
authors.forename: Katrien
authors.initials: K
authors.lastname: De Cocker
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000328:Adult; D000367:Age Factors; D000368:Aged; D001530:Belgium; D003201:Computers; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D057185:Sedentary Behavior; D057566:Self Report; D011795:Surveys and Questionnaires / Q000592:standards*; D013997:Time Factors