title: Girls' perception of physical environmental factors and transportation: reliability and association with physical activity and active transport to school.
abstract: BACKGROUND
  Preliminary evidence suggests that the physical environment and transportation are associated with youth physical activity levels. Only a few studies have examined the association of physical environmental factors on walking and bicycling to school. Therefore, the purpose of this study was (1) to examine the test-retest reliability of a survey designed for youth to assess perceptions of physical environmental factors (e.g. safety, aesthetics, facilities near the home) and transportation, and (2) to describe the associations of these perceptions with both physical activity and active transport to school.
  
  
  METHODS
  Test and retest surveys, administered a median of 12 days later, were conducted with 480 sixth- and eighth-grade girls in or near six U.S. communities. The instrument consisted of 24 questions on safety and aesthetics of the perceived environment and transportation and related facilities. Additionally, girls were asked if they were aware of 14 different recreational facilities offering structured and unstructured activities, and if so, whether they would visit these facilities and the ease with which they could access them. Test-retest reliability was determined using kappa coefficients, overall and separately by grade. Associations with physical activity and active transport to school were examined using mixed model logistic regression (n = 610), adjusting for grade, race/ethnicity, and site.
  
  
  RESULTS
  Item-specific reliabilities for questions assessing perceived safety and aesthetics of the neighborhood ranged from 0.31 to 0.52. Reliabilities of items assessing awareness of and interest in going to the 14 recreational facilities ranged from 0.47 to 0.64. Reliabilities of items assessing transportation ranged from 0.34 to 0.58. Some items on girls' perceptions of perceived safety, aesthetics of the environment, facilities, and transportation were important correlates of physical activity and, in some cases, active transport to school.
  
  
  CONCLUSIONS
  This study provides some psychometric support for the use of the questionnaire on physical environmental factors and transportation for studying physical activity and active transport to school among adolescent girls. Further work can continue to improve reliability of these self-report items and examine their association of these factors with objectively measured physical activity.
authors.affiliation: Department of Epidemiology, School of Public Health, University of North Carolina - Chapel Hill, Chapel Hill, NC, USA. kelly_evenson@unc.edu
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Evenson
authors.forename: Amanda S
authors.initials: AS
authors.lastname: Birnbaum
authors.forename: Ariane L
authors.initials: AL
authors.lastname: Bedimo-Rung
authors.forename: James F
authors.initials: JF
authors.lastname: Sallis
authors.forename: Carolyn C
authors.initials: CC
authors.lastname: Voorhees
authors.forename: Kimberly
authors.initials: K
authors.lastname: Ring
authors.forename: John P
authors.initials: JP
authors.lastname: Elder