[jeffreymoss]

I have a book on the Sony Reader store (Pieces of the Empire) and I noticed my sales ranking in Sci-Fi and Fantasy was at around 2,000 about 5 days ago. I've been following it since then, and my book has moved from that low I just mentioned to around 2,500, constantly bouncing around this range multiple times per day. At one moment I will go up by as much as a couple hundred points, and then I'll go down a similar or less amount.

My theory is that I'm not selling during this time, but that the Sony ranking system is randomly moving my book along this range for some strange reason. I understand that in theory my ranking can only go down if others outsell me (my book is new, so aging of sales should not be a factor) and my ranking can only go up if I either sell books, or that higher ranked books "age-out" and lose ranking to my my more recent sales. So I can imagine that my book reached it's ranking on a sale, and then it could be possible that I've been hit with an more or less equal mix of other books selling and moving past mine, while older books are falling behind mine. That's the best explanation I have. But I'm not sure that makes sense because that would mean an roughly even flow of books going before and after my book over the past 5 days.

Based on my assumption that my book can only go backwards if another book outsells mine, I've calculated that Sony seems to be doing around 500 sales a day in my ranking range (I just added up the spots every time I go backward). That means, in theory, you could fill up the top 2,000 with four days of recent sales. This seems to imply that my best guess is not a likely scenario, as not too many books ranked higher than me should falling behind mine due to aging.

Unfortunately that leaves me with no rational answer to what these rankings might mean other than having a random element.

This matters to me more than for simple ego. I am a new author and I'm trying various ways to market my book, including paid advertising. Sales rankings are the only feedback loop I have to judge if a particular campaign is effective or not, and to what degree. Sony sales rankings seem to offer the most data for me, as they change throughout the day. B&N rankings change daily, so they provide information but with less detail (I rank 320k there overall after having been around 250k a few days ago -- so basically I have two data points to work with). Apple is worthless for sales data, I'm not on Amazon yet, and Smashwords is helpful but not a likely indicator of how I am doing in other stores.

Any words of wisdom out there? I know I'm not selling many books, if any to speak of, I just don't know if I'm selling 0 books in Sony or 4 books a day. At my level, that difference is significant.