Why It's Good for Books to Stay in Print for More than 3 Weeks
Alan Lattimore points to a study of Amazon.com sales ranks carried out by a group of scientists that proves why it might, at least occasionally, be good for publishers to keep books in print for a while, even when they're not immediate bestsellers:
For example, "The Divine Secrets of the Ya-Ya Sisterhood," reached the bestseller lists two years after it came out (and without a major marketing campaign) by making the rounds of book-discussion clubs and inspiring women to form "Ya-Ya Sisterhood" groups of their own. In contrast, an exogenous shock (rave review) appears suddenly and propels a book to bestseller status; however, these sales typically decline rapidly, much more quickly than those that made the charts via word-of-mouth.
In either case, single triggering events (e.g., a mention on "Oprah") appear to have much less effect on the sales history of a book than the actions of interconnected groups of people, who may pick up the book after multiple conversations with acquaintances or by hearing about the book secondhand or by remembering a friend's recommendation months or even years after the book comes out.