Your thoughts on how the results may have been swayed by the user group for the different stores?

I would tend to think that the vast majority of Nook/Kindle Fire consumers are buyers in their natural state. No one buys an E-Reader type device to not acquire books.

However, the overwhelming majority of buyers of the android platform do so, basically to send email, surf the web and maybe even use the phone for texting or calling.

The economic behaviors of the end user may be as much a a factor as any other part of your story.

Would be interesting to know.