title: Differential accuracy of physical activity self-report by body mass index.
abstract: OBJECTIVE
  To examine whether agreement between self-reported and accelerometer-measured physical activity varies by BMI category in a low-income black sample.
  
  
  METHODS
  Participants completed a questionnaire and wore an accelerometer for 4-6 days. Using one- and 10-minute  bouts, accelerometers measured light, moderate, and vigorous physical activity time.
  
  
  RESULTS
  Correlations varied by obesity (nonobese: one-minute r=0.41; 10-minute r=0.47; obese: one-minute r=0.21; 10-minute r=0 .14). Agreement was highest among nonobese persons (one-minute kappa =  0.48, 10-minute kappa = 0.023; obese: one-minute kappa = -0.024, 10- minute kappa = -0.020).
  
  
  CONCLUSIONS
  We found compromised questionnaire performance among obese participants.
authors.affiliation: Department of Epidemiology, Human Development and Health, Harvard School of Public Health, Boston, MA, USA.
authors.forename: Erica T
authors.initials: ET
authors.lastname: Warner
authors.forename: Kathleen Y
authors.initials: KY
authors.lastname: Wolin
authors.forename: Dustin T
authors.initials: DT
authors.lastname: Duncan
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Heil
authors.forename: Sandy
authors.initials: S
authors.lastname: Askew
authors.forename: Gary G
authors.initials: GG
authors.lastname: Bennett
mesh_terms: D056044:Actigraphy / Q000592:standards; D000328:Adult; D015992:Body Mass Index; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology / Q000503:physiopathology; D015203:Reproducibility of Results; D057566:Self Report / Q000592:standards*; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D055815:Young Adult