title: Neighborhood walkability: field validation of geographic information system measures.
abstract: BACKGROUND
  Given the health benefits of walking, there is interest in understanding how physical environments favor walking. Although GIS-derived measures of land-use mix, street connectivity, and residential density are commonly combined into indices to assess how conducive neighborhoods are to walking, field validation of these measures is limited.
  
  
  OBJECTIVE
  To assess the relationship between audit- and GIS-derived measures of overall neighborhood walkability and between objective (audit- and GIS-derived) and participant-reported measures of walkability.
  
  
  METHODS
  Walkability assessments were conducted in 2009. Street-level audits were conducted using a modified version of the Pedestrian Environmental Data Scan. GIS analyses were used to derive land-use mix, street connectivity, and residential density. Participant perceptions were assessed using a self-administered questionnaire. Audit, GIS, and participant-reported indices of walkability were calculated. Spearman correlation coefficients were used to assess the relationships between measures. All analyses were conducted in 2012.
  
  
  RESULTS
  The correlation between audit- and GIS-derived measures of overall walkability was high (R=0.7 [95% CI=0.6, 0.8]); the correlations between objective (audit and GIS-derived) and participant-reported measures were low (R=0.2 [95% CI=0.06, 0.3]; R=0.2 [95% CI=0.04, 0.3], respectively). For comparable audit and participant-reported items, correlations were higher for items that appeared more objective (e.g., sidewalk presence, R=0.4 [95% CI=0.3, 0.5], versus safety, R=0.1 [95% CI=0.003, 0.3]).
  
  
  CONCLUSIONS
  The GIS-derived measure of walkability correlated well with the in-field audit, suggesting that it is reasonable to use GIS-derived measures in place of more labor-intensive audits. Interestingly, neither audit- nor GIS-derived measures correlated well with participants' perceptions of walkability.
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University Health Centre, McGill University, Montréal, Quebec, Canada.
authors.forename: Samantha
authors.initials: S
authors.lastname: Hajna
authors.forename: Kaberi
authors.initials: K
authors.lastname: Dasgupta
authors.forename: Max
authors.initials: M
authors.lastname: Halparin
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Ross
mesh_terms: D016001:Confidence Intervals; D004779:Environment Design; D040362:Geographic Information Systems / Q000592:standards*; D006801:Humans; D011792:Quebec; D012111:Residence Characteristics; D011795:Surveys and Questionnaires; D014505:Urban Population; D016138:Walking