title: Effect of temporal domain on self-reported walking behaviors in the California Health Interview Survey.
abstract: BACKGROUND
  Question design can influence the validity and reliability of physical activity (PA) self-report instruments. This study assesses the effect of temporal domain ("days" walked versus "times" walked) on survey questions about walking behavior.
  
  
  METHODS
  A 2005 California Health Interview Survey (CHIS) subsample (n = 6332) reported the number of days or times they walked for leisure or transportation in the past 7 days and the usual time spent per day or per time. Question order was randomized by temporal domain. Minutes walked per week (mean ± SE) and adherence to PA guidelines (≥150 min/wk) were assessed.
  
  
  RESULTS
  Estimates of leisure walking remained stable across temporal domain (days = 71.4 ± 2.5 min; times = 73.4 ± 2.4 min), but transportation walking differed depending on domain (days = 70.4 ± 3.2 min; times = 52.5 ± 2.6 min). Adherence to PA guidelines based on leisure walking was stable across temporal domain (days = 14.9 ± 0.6%; times = 14.9 ± 0.6%), but again differed by domain for transportation walking (days = 10.4 ± 0.6%; times = 7.8 ± 0.5%). A large order effect (number-of-days versus number-of-times asked first) was observed for reports of days walking for transportation (days first = 87.8 ± 2.9 min; times first = 52.3 ± 2.5 min).
  
  
  CONCLUSIONS
  Temporal domain influences estimates of self-reported transportation walking behavior. Current efforts to capture PA from both transportation and leisure activities in health research appear to present distinct methodological challenges.
authors.affiliation: Cancer Prevention Fellowship Program, National Cancer Institute, Bethesda, MD, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: McClain
authors.forename: David
authors.initials: D
authors.lastname: Grant
authors.forename: Gordon
authors.initials: G
authors.lastname: Willis
authors.forename: David
authors.initials: D
authors.lastname: Berrigan
mesh_terms: D000293:Adolescent; D000328:Adult; D002140:California; D005260:Female; D006306:Health Surveys; D006801:Humans; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D015203:Reproducibility of Results; D057566:Self Report; D013997:Time Factors; D016138:Walking / Q000502:physiology*; D055815:Young Adult