Without delving too deeply into the methodology, these numbers appear sound enough. Here I was thinking I was in the minority reading from a PC (10" laptop), and it turns out I'm the norm
I keep saying it will be small laptops and big smartphones that blow up the ebook market, and these numbers are consistent with my thesis, though we can't say much conclusively until ebooks are more like 15-20% of sales, rather than 1.5%.