Unlike Nielsen’s BookScan, which gives industry subscribers actual sales numbers at 4,500 retail outlets, the Times list, like those of other newspapers, gives only a book’s ranking. USA Today and The Wall Street Journal, two competing national newspapers, name the booksellers they survey. The Times refuses to do that for fear that someone will try to game the system — for example, making strategic bulk buys to inflate sales numbers. When bulk purchases are reported, The Times puts the symbol of a dagger beside the book’s title to alert readers.