So much for “Customers Who Bought This Item Also Bought …” and “Frequently Bought Together”: A fascinating dispatch in Forbes reports that less than 10% of book purchases on Amazon are spontaneous reactions to the site’s constant suggestions of related items. Most sales are in fact “from people who already know what they want and are simply using Amazon as a way to get it.” A “whopping” 48% of book purchases are made by customers who search by author or topic.

The Forbes report, by contributor Suw Charman-Anderson, summarizes a presentation at the Digital Media Strategies conference by Douglas McCabe, COO of Enders Analysis. As summarized by Anderson:

McCabe’s statistics show that only a piddling 10 percent of Amazon book choices are made because of its ‘bought this/also bought’ recommendation engine. Bestseller and top 100 lists influence 17 percent of book choices, with 12 percent down to promotions, deals, or low prices. Only 3 percent came through browsing categories. Planned search by author or topic, however, makes up a whopping 48 percent of all book choices.

Anderson further notes:

The title of McCabe’s slide is “Amazon – only the end of the funnel, so far?”[and it shows that] Amazon is a destination for purchase, the place you funnel your fans to, not a discovery mechanism in and of itself. People are simply not browsing for books based on Amazon’s recommendations, not in any significant numbers.

McCabe’s numbers won’t come as much of a surprise to students of Amazon, which has long relied on so-called “showrooming,” which studies have shown accounts for nearly 40% of Amazon book sales. That is, nearly 40 percent of customers who buy books online, such surveys have found, have seen them in a brick-and-mortar bookstore first. (See this 2011 MobyLives report for more on one such study.)

According to Anderson, the new numbers have “huge implications” for how publishers market books online. Since the decision to buy “has been formed outside of Amazon, perhaps due to reviews, social media or word of mouth,” publishers (who, by the way, pay Amazon’s steadily increasing fees for placement in things like “Customers Who Bought This Item Also Bought …”)  should in fact continue to focus their efforts on spreading the word about their books by means outside of the Amazon bubble.