title: Assessing urban and rural neighborhood characteristics using audit and GIS data: derivation and reliability of constructs.
abstract: BACKGROUND
  Measures to assess neighborhood environments are needed to better understand the salient features that may enhance outdoor physical activities, such as walking and bicycling for transport or leisure. The purpose of this study was to derive constructs to describe neighborhoods using both primary (neighborhood audit) and secondary (geographic information systems) data.
  
  
  METHODS
  We collected detailed information on 10,770 road segments using an audit and secondary data. The road segment sample was randomly split into an exploratory (60%) and validation sample (40%) for cross-validation. Using the exploratory sample (n = 6,388), seven a priori constructs were assessed separately (functionality, safety, aesthetics, destinations, incivilities, territorality, social spaces) by urbanicity using multi-group confirmatory factor analysis (CFA). Additionally, new a posteriori constructs were derived using exploratory factor analysis (EFA). For cross-validation (n = 4,382), we tested factor loadings, thresholds, correlated errors, and correlations among a posteriori constructs between the two subsamples. Two-week test-retest reliability of the final constructs using a subsample of road segments (n = 464) was examined using Spearman correlation coefficients.
  
  
  RESULTS
  CFA indicated the a priori constructs did not hold in this geographic area, with the exception of physical incivilities. Therefore, we used EFA to derive a four-factor solution on the exploratory sample: arterial or thoroughfare, walkable neighborhood, physical incivilities, and decoration. Using CFA on the validation sample, the internal validity for these a posteriori constructs was high (range 0.43 to 0.73) and the fit was acceptable. Spearman correlations indicated the arterial or thoroughfare factor displayed near perfect reliability in both urban and rural segments (r = 0.96). Both the physical incivilities factor and the walkable neighborhood factor had substantial to near perfect reliability in both urban and rural segments (r = 0.77 to 0.78 and r = 0.79 to 0.82, respectively). The decoration factor displayed moderate reliability in urban segments (r = 0.50; 95% CI: 0.38-0.60) and lower reliability in rural segments (r = 0.39; 95% CI: 0.25-0.52).
  
  
  CONCLUSIONS
  The results of our analyses yielded four reliably and objectively measured constructs that will be used to explore associations with physical activity in urban and rural North Carolina. These constructs should be explored in other geographic areas to confirm their usefulness elsewhere.
authors.affiliation: Department of Epidemiology, Gillings School of Global 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: Daniela
authors.initials: D
authors.lastname: Sotres-Alvarez
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.forename: Lynne
authors.initials: L
authors.lastname: Messer
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Laraia
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Rodríguez