I'm a big numbers nut myself, and I've developed a bit of a niche writing about publishing industry book sales. Which reminds me, I heard back from the census bureau and they don't include Amazon in their bookstore sales stats. But this post is in reaction to an e-mail from a writer considering one of the big subsidy publishers, or author services companies, in which he enclosed some of their boasting about sales.
They claimed to have books in over a million American households. Now, I'm not sure how one goes about substantiating a claim like this, my guess is, they have shipped over a million books and feel free to translate a million shipments into a million households. It sounds like a big number, until you consider they have published around 25,000 titles. That works out to "over" 40 copies per title, shipped. That doesn't sound so impressive anymore. It would be interesting to know how many shipments represented the sale of a book to a customer other than the author. If most authors are buying copies to send to reviewers, family and friends, you could end up with a very low number for "real" sales indeed.
Another claim was that a book is ordered by a bookstore every three minutes, around the clock, seven days a week. A sale every three minutes means 20 sales per hour, or 480 sales per day. Spread that over 25,000 titles, and you get an average sales rate of just over one copy every two months, or about seven copies per title per year. Again, a couple of those are no doubt ordered by the authors themselves, just to make sure the system works, or the author's mother, just to make sure the author doesn't go ballistic. The point is, next time a publisher of any ilk tries to dazzle you with their sales, sit down and do the math. It may turn out that they are being more honest than they intended. Selling seven copies per title per year through bookstores doesn't quite jive with their claims to be a traditional publisher:-)