I work in the data collection industry, if not the retail and book-data collection industry (!), and know that all data is inaccurate to some degree. You can only ever get a true picture from a consensus – asking ALL retailers. Which is basically impossible. So my only advice is simple advice: Forget about it. Those that need to know how well a book is selling, publishers and creators, will do from their revenue. And us? The ordinary punter? We’ll find out by whether the book is still available month after month and the sale price. A deep discount on the remainding copies of Gunslinger doesn’t sound too good does it? So, whatever boost it got from the sale, I’d say it’s pretty safe to assume that lately it’s sales have been weak. So this tells us that the Times book chart IS probably inaccurate as feck, but can any of you honestly come up with a better way of tracking sales? I mean noone has yet suggested what the Times SHOULD be doing, just slagging off their system — which is a mkystery to us all anyway.

All in all, this whole discussion seems a bit pointless to me. And, although I feel I should end this little rant soon, can I just say that I’ve heard similarly dismissive views of the Diamond data you were so keen on comparing the Times data to. I mean, for hecks sake, I hear things here in Blighty about how UK unemployment data — something as important as the livelihood of 60 million people — is unreliable and skewed to heck by issues regarding what qualifies. So, please, end this now. You’ll never get to the bottom of it..

I suppose I too would be a little surprised at any but the smallest retailer (in any kind of business) that doesn’t have a cash register or POS-system. But though I think that alternate paper-based means are surely less efficient, I wouldn’t conclude that they are automatically inaccurate or ineffective. (Heck, there were retailers successfully retailing for years, or decades, or centuries, before the advent of computerized cash registers…)