Online recommendations are more effective with certain categories of books and price points, according to a 2006 study, _ The Dynamics of Viral Marketing_. Researchers at HP Labs and two universities reviewed millions of book purchases resulting from online recommendations.
Recommendations for medical texts tended to be most effective--nearly 5.7 percent of them resulted in a purchase, almost double the average rate. The researchers attributed this to the higher median price of medical books and technical books in general. A higher book price increased the chance that recommendations would be consulted and accepted.
Recommendations were moderately effective for certain religious categories: 4.3 percent for Christian living and theology, and 4.8 percent for Bibles. By contrast, books not connected with organized religions had lower recommendation effectiveness, including New Age (2.5 percent) and occult (2.2 percent).
Recommendations for fiction books were usually the least effective, with only about 2 percent resulting in purchases. Recommendations for nonfiction books dealing with personal and leisure pursuits were slightly more effective, resulting in purchases about 3 percent of the time.
Two book recommendation networks. The left shows how recommendations for a study guide were ineffective and ignored by consumers. On the right, recommendations for a graphic novel were effective, resulting in frequent purchases.
The book on the left is the study guide _First Aid for the USMLE Step 1. _The book on the right is _Oh My Goddess!: Mara Strikes Back. _ Recommendations for this graphic novel prompted bursts of connected sales represented visually by the linked patterns. The opportunities for networking are vast: Japanese comics have a wide following in the United States, are popular with children and adults, and are vigorously supported by online communities. By contrast, suggestions for study guides usually originate outside online communities, from an instructor or employer. Choice is restricted, online connections are sparse, and no word of mouth occurs. For a variety of reasons, readers are rarely passionate about textbooks.
Generally, though, fiction recommendations are least effective of any book category, resulting in purchases only 2 percent of the time, while recommendations for expensive medical books are most effective.
_Illustration from _ The Dynamics of Viral Marketing
_ by Leskovec, Adamic, Huberman._
Recommendations from family members or personal friends were much more effective for fiction and religious books than online recommendations, the researchers concluded.
Some book categories, such as gardening, have different recommendation effectiveness depending on how specialized the text and how widely the topic is supported by online communities. For example, books on vegetable or tomato growing had only average recommendation effectiveness compared with other nonfiction. However, recommendations of books on orchid cultivation, which tend to be more specialized, had double the recommendation acceptance.
Customers are more likely to buy a book if they receive the same recommendation twice. After that, customers tend to ignore the recommendation.
The study is available in its entirety here: