<P> The exact method for compiling the data obtained from the booksellers is classified as a trade secret . Book Review staff editor Gregory Cowles explained the method "is a secret both to protect our product and to make sure people can't try to rig the system . Even in the Book Review itself, we don't know (the news surveys department's) precise methods ." In 1992, the survey encompassed over 3,000 bookstores as well as "representative wholesalers with more than 28,000 other retail outlets, including variety stores and supermarkets ." By 2004, the number was 4,000 bookstores as well as an unstated number of wholesalers . Data is adjusted to give more weight to independent book stores, which are underrepresented in the sample . </P> <P> The lists are divided among fiction and non-fiction, print and e-book, paperback and hardcover; each list contains 15 to 20 titles . The lists have been subdivided several times . "Advice, How - To, and Miscellaneous" debuted as a list of five on January 1, 1984 . It was created because advice best - sellers were sometimes crowding the general non-fiction list . Its inaugural number one bestseller, The Body Principal by Victoria Principal, had been number 10 and number 12 on the non-fiction lists for the two preceding weeks . In July 2000, the "Children's Best Sellers" was created after the Harry Potter series had stayed in the top spots on the fiction list for an extended period of time . The children's list was printed monthly until Feb. 13, 2011, when it was changed to once an issue (weekly). In September 2007, the paperback fiction list was divided into "trade" and "mass - market" sections, in order to give more visibility to the trade paperbacks that were more often reviewed by the newspaper itself . In November 2010, The New York Times announced it would be tracking e-book best - seller lists in fiction and nonfiction starting in early 2011 . "RoyaltyShare, a San Diego - based company that tracks data and aggregates sales information for publishers, will...provide (e-book) data". The two new e-book lists were first published with the February 13, 2011, issue, the first tracks combined print and e-book sales, the second tracks e-book sales only (both lists are further sub-divided into Fiction and Non-fiction). In addition a third new list was published on the web only, which tracks combined print sales (hardcover and paperback) in fiction and nonfiction . In December 16, 2012, the children's chapter books list was divided into two new lists: middle - grade (ages 8--12) and young adult (age 12--18), both which include sales across all platforms (hard, paper and e-book). </P> <P> The list has been criticized by authors, publishers, book industry executives, and others for not providing an accurate accounting of true best - seller status . These criticisms have been ongoing ever since the list originated . A book industry report in the 1940s found that best - seller lists were a poor indicator of sales, since they were based on misleading data and were only measuring fast sales (see "fast sale" criticism below). A 2004 report quoted a senior book marketing executive who said the rankings were "smoke and mirrors"; while a report in Book History found that many professionals in the book industry "scoffed at the notion that the lists are accurate". </P> <P> Specific criticisms include: </P>

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