Two salient features emerged from our analysis of the food-purchase data of sixty-four families for a four-year period. One is the nonvarability over time of the number of acyclically ordered bundles for each family, and the other is the pattern of seasonal stability within each year. Our finding that consistent (or inconsistent) behavior in accordance with the axioms of revealed preference is an observable family characteristic is corroborated by a separate study on demand functions using the same data. To facilitate data processing, the revealed preference relations were expressed and sorted out in Boolean matrices.