Environmental measures of physical activity supports - Perception versus reality

Background: Perceptions of the environment and physical activity have been associated using survey methods, yet little is known about the validity of environmental surveys. In this study, perceptions of the environment at neighborhood and community levels were assessed (1) to determine validity by comparing respondent perceptions to objective measures and (2) to determine test-retest reliability of the survey. Methods: A telephone survey was administered to a stratified sample of Sumter County, South Carolina adults. Respondents' home addresses were mapped using a geographic information system (GIS) (n = 1112). As an indicator of validity, kappa statistics were used to measure agreement between perceptions and objective measures identified at neighborhood and community levels using GIS. A second survey in an independent sample (n = 408) assessed test-retest reliability. Results: When assessing perceptions of environmental and physical activity in a defined geographic area, validity and reliability for neighborhood survey items were kappa = -0.02 to 0.37 and rho = 0.42 to 0.74, and for community survey items were kappa = -0.07 to 0.25 and rho = 0.28 to 0.56. Conclusions: Although causality between perception of access and safety and actual physical activity level cannot be assumed, those meeting national physical activity guidelines or reporting some physical activity demonstrated greatest agreement with access to recreation facilities, while those not meeting the guidelines demonstrated greater agreement with safety of recreation facilities. Factors such as distance and behavior may explain differences in perceptions at neighborhood and community levels. Using local environments with short distances in survey methods improves validity and reliability of results.