This chapter explains why the purchase funnel – sometimes known as the “consumer decision journey” or the “consumer buying path” – is a valuable analytical framework for marketing experts engaged to provide an external expert opinion to inform the finder of fact in litigation matters. The value inherent in the purchase funnel framework is that, unlike most economic analyses or analyses grounded in the strategy literature, the purchase funnel does not treat consumers as making a single discrete decision. Instead, it recognizes that for each decision that any one consumer makes, the consumer must pass through a series of distinct hurdles progressing from awareness to consideration, conversion, and post-purchase. Laying out these steps can be helpful in a large variety of litigation contexts.