Okay, first you have to understand how "lists" work. There are two kinds of bestseller lists.
1.
Point of Sale lists -- The USA Today, and BookScan (a publishing-industry report of book sales) lists are based on "point of sale," meaning that every cash register ring of a book to the public in certain PRIMARY or SECONDARY market stores is counted. Now, a primary market is a B&N, Walden's, BAMM, Amazon, etc. A secondary market is WalMart, Target, Costco, Anderson News (which distributes to many of the grocery chains), Sam's Club, etc. Each list takes a different number. It APPEARS (and I could be wrong on this) but sales of about 3,500 books nationwide will get the book an appearance on USA Today. Format (hardback, trade, mass paperback) doesn't matter, because they all compete against each other, in all genres. It only takes about 900-1,000 to make a BookScan Top 100 list--but those are divided into genre lists. Library Journal is another point of sale list, but is based on sales to... (duh!) libraries.
2.
Book order lists. You have to remember that the PUBLIC is not the publisher's actual customer. Never has been. The BOOKSTORE (distributor, wholesaler, etc.) is the primary customer of a publisher. When a bookstore's buyer orders the book, it's "sold" just as plainly and completely as when it is later "sold" to the public. Both the NYTimes list and Publisher's Weekly list are based on book orders. This is why a book (like Harry Potter) can appear on top of the NYTimes list before it's ever released. That would never happen with the USAToday list. But like blue moon says, then things start to get weird. Certain stores (at different booksellers in different parts of the country) receive a form to fill out once a week. On that form is a long list of book titles. The manager of that store is supposed to fill out how many copies of each book have been ordered. Now, since this is a weekly list, that also means RE-orders (which is how most books wind up on the list--except in unusual cases where a store expects the demand to be big on opening day.) The faster the books sell in the store, the more are re-ordered.
However (and here's the interesting part!) only books ON the form are counted. Not every book is on the form. Now, a bookstore can add a book to the form, but it has to be selling exceptionally well for a bookstore manager to REMEMBER it to write it down.
The number of sales to appear on either NYTimes or PW depends drastically on a weighted average. For example, if Jim's latest Harry hardback had been pubbed THIS month instead of May, it probably wouldn't have made the list. It would have had to compete with all of the "required reading" books for back to school. Tough to beat out sales of Animal Farm and Farenheit 451 this month! Yeah, publishers really think about stuff like this when they're picking slots for publication. They don't just assign a random month to books with the
potential to make a list. They really do try to give it every advantage, because once a book hits a list, the next one probably will too and sales can only go up from there, because both USAToday and NYTimes are looked at by a wide swath of the public that their marketing could never HOPE to reach.
I just learned all this strange stuff a few months back, because we learned that our latest book just made an appearance on "the form." So NYTimes is starting to track our sales. Whee!
There's your marketing lesson for the day.