title: Comparing physical activity questionnaires for youth: seasonal vs annual format.
abstract: BACKGROUND
  In large cohort studies of older children, self-report is the only practical way to assess physical activity. Assessing usual activity over the entire year is desirable, but children and adolescents may overestimate activities with high seasonal variability. Use of questionnaires in which individuals report each activity by season may improve accuracy.
  
  
  METHODS
  A total of 6782 girls and 5110 boys, aged 9-14 years in 1996, completed self-administered activity questionnaires in 1996 and in 1997. In 1996, participants reported the average time spent in each of 17 activities during the previous 12 months; in 1997, we also asked for the average time spent in the previous year, but within each of the four seasons.
  
  
  RESULTS
  Girls reported a median of 12.8 hours/week total activity in 1996 and 10.4 hours/week in 1997. For boys, the estimates were 15.5 hours/week and 13.4 hours/week, respectively. Girls and boys within 1-year age strata (e.g., comparison of 10-year olds in 1996 with 10-year olds in 1997) reported an average of 3.7 and 3.1 fewer hours per week, respectively, on the 1997 seasonal format versus the 1996 annual format questionnaire. In longitudinal analyses, the difference between the annual and the seasonal estimates was greater if participants did the activity in fewer seasons in 1997.
  
  
  CONCLUSIONS
  In comparison to an annual format questionnaire, a seasonal format questionnaire may improve accuracy of self-report of physical activity by reducing over-reporting of activities in which pre-adolescents and adolescents engage in fewer seasons.
authors.affiliation: Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, Massachusetts 02215, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Rifas-Shiman
authors.forename: M W
authors.initials: MW
authors.lastname: Gillman
authors.forename: A E
authors.initials: AE
authors.lastname: Field
authors.forename: A L
authors.initials: AL
authors.lastname: Frazier
authors.forename: C S
authors.initials: CS
authors.lastname: Berkey
authors.forename: C A
authors.initials: CA
authors.lastname: Tomeo
authors.forename: G A
authors.initials: GA
authors.lastname: Colditz
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D015203:Reproducibility of Results; D013177:Sports / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires / Q000145:classification