Understanding customer buying patterns is of great interest to the retail industry. Association rule mining is a common technique for extracting correlations such as people in the South of France buy rosé wine or customers who buy paté also buy salted butter and sour bread. Unfortunately, sifting through a high number of buying patterns is not useful in practice, because of the predominance of popular products in the top rules. As a result, a number of " interestingness " measures (over 30) have been proposed to rank rules. However, there is no agreement on which measures are more appropriate for retail data. Moreover, since pattern mining algorithms output thousands of association rules for each product, the ability for an analyst to rely on ranking measures to identify the most interesting ones is crucial. In this paper, we develop CAPA (Comparative Analysis of PAtterns), a framework that provides analysts with the ability to compare different rule rankings. We report on how we used CAPA to compare 34 interestingness measures applied to patterns extracted from customer receipts of more than 1,800 stores for a period of one year.