1. A method for quantifying and discovering patterns in relationships between entities comprising products and customers, as evidenced by purchase behavior, the method comprising the steps of: applying consistency and similarity functions to transaction data generated by said entities; performing a statistical analysis of statistically significant and logical associations between products; and analyzing product associations in a plurality of contexts comprising any of individual market baskets, a next visit market basket, or across all purchases in an interval of time; wherein different kinds of purchase behavior associated with different types of products and different types of customer segments are revealed.