This guest post, by April L. Hamilton, originally appeared on Alan Baxter’s The Word on 1/2/11.
My new publishing series continues today with a post from April Hamilton called “How Meaningful A Metric Is Your Book’s Amazon Sales Rank?”, which is, obviously, all about the sales rank on Amazon. It makes for some pretty interesting reading. Check the links is April’s bio at the end, as there’s some good stuff in there. All yours, April:
How Meaningful A Metric Is Your Book’s Amazon Sales Rank?
Ah yes, the Amazon Sales Rank: that addictive bit of eye candy that can lift an author’s spirits into the stratosphere one day and hurl him down onto the rocks the next. In all likelihood neither reaction is truly justified, because a book’s Amazon Sales Rank is a temporary, relative thing, and does not mean what many authors think it does. If you want to get to the bottom of what your book’s ASR means, you might start by thinking about what the ASR does not mean.
First, it does not reflect a cumulative sales count. Let’s say Amazon has 1 million titles listed for sale on its site—it actually lists many more than that, but let’s keep the math simple. Let’s further say that Amazon opened its virtual doors exactly one year ago today, and your book is currently ranked #500,000. It would seem logical to assume the book that has sold the fewest copies over the past year would be ranked #1,000,000, the one that has sold the most copies would be ranked #1, and yours, ranked at #500,000, has sold exactly 499,000 fewer copies than #1 and 499,000 copies more than #1,000,000. But this is not true at all. Your book’s ASR is based on a much more complex algorithm that’s considered a trade secret by Amazon.
Second, your book’s ASR is not a dynamic line such as one might see on a sales chart, moving reliably upward each time a copy sells, and just as reliably downward when others’ books are selling and yours is not. ASR is recalculated hourly, and only includes titles that actually had sales activity during the hour in question, or were ranked within the top 100 in any category during that hour. This is how it’s possible for your book’s ASR to sometimes be higher than that of multi-million-selling books by authors along the lines of JK Rowling and Stephen King; if neither of them sold any copies in a given hour when you sold 2 copies of your book, your book’s rank will be higher than theirs’ for that hour. Your book is only being ranked relative to the performance of a small subset of all the books being offered for sale by Amazon.com.