An issue that came up several times during the workshop, including in this discussion, centered on realistic expectations from introducing a new supermarket into a food desert, in terms of changes in food intake and ultimately BMI or other health outcomes. The natural experiments with which Cummins has been involved led him to realize, he said, that robust underlying theoretical models and the time frames in which we might realistically see effects are still not fully known. One successful outcome could simply be increasing the number of food stores available, but a secondary outcome would be to see changes in health behaviors and then impacts on obesity or the prevalence of diabetes. Changes in important health behaviors and outcomes may take longer to ascertain than most current funding mechanisms allow. Diez Roux suggested looking at proximal outcomes in the short term, rather than trying to detect more distal effects.
Cummins also suggested making more use of complementary activities, such as mailings to residents or incentives, and evaluating the effect of these initiatives combined with changes in supply.
One workshop participant questioned whether food desert health outcomes are really due to limited food access or perhaps more likely to limited healthcare access. Diez Roux agreed the issues are confounded because the real world is complex, and it is difficult to separate the causal effect of food access. Methodologically, researchers attempt to create boundaries through a variety of statistical controls. Cummins said spatial analytic approaches to measure access using GIS (geographic information systems) in longitudinal studies may help avoid the problem of using administrative boundaries, which may shift over time, as a proxy for neighborhoods. People have different perceptions of neighborhood boundaries. Using census tracts as a proxy, in his opinion, also has weaknesses that qualitative research reveals. Questions remain about what is the most relevant and comparable spatial environment. Diez Roux agreed that a census tract is not ideal, but may serve as a useful although imperfect proxy for the most relevant spatial context.
Reedy summarized several questions from workshop participants related to work within communities. Partnering with community groups to conduct research is important in this kind of research, said Diez Roux, particularly in evaluating natural experiments and conducting qualitative studies.
Studies have looked at various community benefits of addressing food issues. Urban agriculture is promoted in some cities to increase local