Differences in accessibility spatial measures: Implications for community strategy

Recently the increased focus on community context on health behavior has led to a growing number of studies exploring how access to food stores differs by sociodemographic characteristics, especially race and income. However, few studies have compared the results of different accessibility measures to explore how they differ. In the public health literature there has been little to no discussion about why a specific accessibility measure should be chosen or whether the results of one measure can be compared to another. This study compared 6 measures of spatial access to supermarkets in the Chicago Metropolitan Area. Each accessibility measure identified different locations and patterns of high access and low access. Results illustrated that several issues need to be taken into account when studying access. First, the question needs to be matched to the measure, as each showed clear differences in the identification of high and low access. Second, the issues of independence and spatial dependency need to be addressed in the statistical analysis. Third, the size of the geographic area chosen to study can bias results. The implications of these findings will be applied to the interpretation of previous and future studies.