The hunt for the key has been much more extensive in other industries, which have made a point of using new technology to gain a better understanding of their customers. Television stations have created online forums for viewers and may use the information there to make programming decisions. Game developers solicit input from users through virtual communities over the Internet. Airlines and hotels have developed increasingly sophisticated databases of customers.

Publishers, by contrast, put up Web sites where, in some cases, readers can sign up for announcements of new titles. But information rarely flows the other way -- from readers back to the editors. . . .

But results are not spectacular, for an industry that had $34.6 billion in net revenue in 2005. Net profit margins hover in the mid-single digits for the $14 billion trade segment, which covers adult, juvenile and mass market titles, with an estimated 70 percent of titles in the red.

The industry does follow trends to pursue growth, but when it comes to acquisitions, methods have not changed much in hundreds of years, says Al Greco, a professor of marketing at Fordham University. . . .

All of the major houses have also lost on big bets. One of the highest advances ever paid was more than $8 million for a proposal that became ''Thirteen Moons,'' the second novel by Charles Frazier. He is the author of ''Cold Mountain,'' which sold 1.6 million copies in hardcover.

Random House printed 750,000 copies of ''Thirteen Moons'' for the hardcover release in October. The book became a best seller, but it has sold only 240,000 copies so far, according to Nielsen BookScan. That would account for less than $1 million of earned royalties, under standard contract terms. The paperback will be out next month, further diminishing hopes of selling out even the initial hardcover print run. . . .

There are two ways for a book to become a best seller. One is to make it on to a best-seller list by selling many copies in a week. Other books sell steadily over months and years, eventually outselling many official best sellers. ''Unanswered Cries,'' a true-crime book by Tom French, was acquired in 1989 by St. Martin's for $30,000. It now has 400,000 copies in print in paperback and sold at least 31,000 copies last year alone.

These older titles are crucial to profits because marketing and acquisition costs have usually already been recouped. Yet publishers focus much more attention on the hardcover release. As they prepare to introduce a book, any combination of timing, packaging, marketing and other factors could help ignite the mysterious spark that leads to best-sellerdom.

Contributing to the success of ''The Secret,'' for example, could be any or all of the following: the subject, the title, the initial DVD release, the marketing campaign, the power of the Internet, ''Oprah'' and the latest trend.

But ''The Secret'' is only the most recent book of its type. ''Many people have spent lots of money trying to publish the book 'The Secret' has become,'' says Susan Petersen Kennedy, president of the Penguin Group. ''A lot of books are just like that that haven't worked.'' . . . .

Most publishers, though, continue to gather data on sales and not much else, though past performance is certainly no guarantee of future results, even from the same author.

After ''Prep'' became a best seller, Random House signed a two-book deal with Ms. Sittenfeld for a multiple of her $40,000 ''Prep'' advance that she would not reveal.

Her second coming-of-age novel, ''The Man of My Dreams,'' was published last May, and again the advance payment and sales haven't matched up. According to Nielsen BookScan, ''The Man of My Dreams'' has sold 36,000 copies in hardcover and 6,000 in paperback.

Ms. Sittenfeld says she is reminded of something she heard from an editor: ''People think publishing is a business, but it's a casino.''

If the article is correct, then I find it quite surprising that book publishers haven't done more to understand their market. Perhaps it is impossible to predict what will make a book sell. It's not quality, as many fantastic books don't sell well, and many terrible books fly off the shelves. I doubt that it is marketing that catapults a book to the bestseller list. Few publishers expend much resources in marketing -- and those resources go only to a select few books. If only somebody knew the answer. . . .