Amazon has put forward an apparently stunning piece of news: Over the past three months, for every 100 hardcover books Amazon.com has sold, it has sold 143 Kindle books.

Indeed, it goes further: “Over the past month, for every 100 hardcover books Amazon.com has sold, it has sold 180 Kindle books,” we’re told. It’s an impressive line that’s being parroted by the NYT and others.

Except, Derek points out, it’s probably not stunning at all.

Amazon is usually reticent to share more information than is convenient for its image. I’ve encountered this plenty of times, especially in regard to the Kindle, so all I’m left with are questions.

Has there been a decrease in the actual number of hardback sales? Is the increase in ebook sales additive to the overall market? What has the action been like in paperback? Where does price sensitivity play a part here? What’s Amazon’s promotional strategy like regarding hardcovers during the period in question? What impact does seasonality have on these numbers?

Essentially, I’m left thinking about a number of scenarios. Here are just a few; and there are probably many, many others that could all be in play at the same time.

a) voracious consumers of brand-new titles are switching to ebooks because of price and/or convenience
b) a sizeable number of hardbacks are of a sort (ie reference) that tend towards e-versions
c) new ereader owners are a fresh category of disproportionately high spenders
d) ebook versions are cannibalizing all physical sales (hard and paperback)
e) the iPad and others have helped create a fresh interest in ebook sales in general
f) the iPad and others have helped create a bump in Kindle sales
g) more marketing spend is going on trying to plump up the ebook category

etc etc

So is the pie bigger overall, or smaller? What exactly is Amazon trying to tell us about reading?

Every story like this needs to be approached with more than a little scepticism. It seems to me that Amazon — which, unlike Apple, sells physical and digital versions of titles — is in a unique position to alter customer behavior and then crow about that alteration.