The New York Times also states that it applies certain standards and definitions to its data, such as excluding textbooks, reference books, test preparation guides, journals, workbooks, crossword puzzles, etc.
It also excludes sales from certain online retailers, such as Amazon.com and Barnes & Noble.com, as well as sales from book clubs, libraries, and self-published books (unless they are distributed by a major publisher).
The Times also adjusts its data for seasonal variations and other factors that may affect sales patterns.
The New York Times does not rank all the books that are reported to it, but only those that meet its editorial standards.
The number of books on each list varies depending on the number of eligible titles and the space available in the print edition of The New York Times Book Review.
The lists are divided into several categories:
- fiction (hardcover, paperback trade fiction, paperback mass-market fiction),
- nonfiction (hardcover, paperback trade nonfiction),
- children’s books (picture books, middle grade hardcover, young adult hardcover), a
- dvice/how-to/miscellaneous (hardcover), business (hardcover),
- graphic books (hardcover/paperback),
- manga (paperback),
- audio fiction/nonfiction (monthly),
- e-books (combined fiction/nonfiction),
- combined print & e-book fiction/nonfiction.
The ranking of each book on each list is determined by a formula that weights sales according to the type of venue where they are sold: independent bookstores have more influence than chain bookstores; general bookstores have more influence than specialty bookstores; etc.
The formula also takes into account other factors such as longevity on the list, price of the book, format of the book, etc. The exact formula is not disclosed by The New York Times.
The lists are compiled by The New York Times staff editors based on the sales data provided by Nielsen BookScan and other sources.
The editors also have discretion to exclude or include certain titles based on their judgment of quality, relevance, and appropriateness for their audience. The editors may also consult with outside experts or reviewers to evaluate certain books or genres.
