Knowledge of a high correlation between a consumer’s residence and his place of grocery shopping has allowed researchers to use scanner data to assess the relationship between income and shopping behavior. This study addresses the shopping behavior of over 100,000 consumers who patronize six supermarkets weekly. Three of these supermarkets are best characterized as stores that service primarily lower-income shoppers, and three are best characterized as stores that service primarily higher-income shoppers. A key objective of this research is to determine if purchasing patterns differ for the two income groups and, if so, to determine if these differences are consistent with economic theory. The results show that the dominant income group for a given area makes purchase decisions that are so widespread and prominent that the confounding effects of other income shoppers are completely overshadowed. Simply stated, the statistical evidence is so strong that it overcomes all possible deviating effects which may result from data outliers.