The Impact of Display Advertising

One mistake easy, in fact, almost impossible to avoid when evaluating the return on investment of display advertising is to attribute buying actions to the "last channel" a customer uses when making a purchase.

By that logic, the best channel a retailer has is a cash register at a store or the ordering function of a website. That's the "channel" we can measure as registering a sale. What is difficult, nearly impossible to measure is all the other influences that have lead up to a purchase. Those influences are, by definition, indirect in the sense that all of them, or some of them, have had a rule in moving a particular buyer to purchase activity.

Some will argue that channels play different roles, at different parts of a buying cycle. Display advertising, word of mouth, recommendations and online content do the "heavy lifting" early in the consumer decision-making process of driving awareness and consideration.

The argument is that prospects often have initial exposure in the research phase that later produces a "buyer." A late-stage visit often gets credited to search marketing, when a user already has made a decision, and is looking for the actual sales channel.

So the temptation is to credit the entire sale to the search channel. That's a mistake of attribution. It can be unknowable how any particular prospect became a buyer, but it likely is the case that multiple information or advertising and promotion channels played a role.

The Impact of Display on Search | ClickZ