spatial relationships (Leslie et al., 2005). The use of GIS provides objective measures of the environment and can be used to supplement or replace self-report measures (Porter et al., 2004). GIS technologies are increasingly being used for public health applications and have been used to examine a range of issues of relevance to childhood obesity prevention including the walkability of communities (Handy et al., 2002; Leslie et al., 2005), access to recreational facilities (Gordon-Larsen et al., 2006), and the accessibility of stores that sell fresh produce to food pantry clients who do not have access to fresh fruits and vegetables through most emergency food assistance programs (Algert et al., 2006).
Largely a tool used by researchers, GIS capabilities are now more easily accessible to community organizations, although much remains to be learned about how this technology can be used most effectively at the community level (Porter et al., 2004). A recent CDC and University of New Mexico effort in partnership with American Indian and Alaskan Native communities, Mapping a Shared Vision of Hope, is using GIS technology to provide data and maps relevant to diabetes prevention (Mapping a Vision, 2006). This tool provides spatial distribution data for a range of health and social variables.
As more community information is available in online and mapped formats, increased opportunities become available for mapping multiple facets of community life and identifying strengths and opportunities for promoting physical activity and access to healthful foods in the community (Porter et al., 2004). Presentation of the data visually to community stakeholders has the potential to be an important tool in engaging and tracking community obesity prevention efforts, particularly because they can be focused on a local geographic area. The committee encourages increased exploration and use of GIS and other relevant technologies for the development and evaluation of community-level interventions to promote energy balance in youth.
The realities of the changes that occur in communities pose challenges to the implementation of evaluation research. Often, changes that are relevant to obesity prevention (e.g., a new school policy or a new park or walking path) are not under the control of researchers or are under way before researchers have the time to institute traditional research methodologies or apply for evaluation funding through lengthy funding processes. These events are often called natural experiments as they offer a unique opportunity to compare rates of obesity and intermediate indicators before and after the change. To evaluate these natural experiments, mechanisms