Print power buyers make up 22 percent of the overall print book-buying population, and they drive 53 percent of print book purchases overall.
Meanwhile, e-book power buyers make up 35 percent of the overall e-book buying population, but they drive 60 percent of overall e-book purchases. In other words, about a third of the overall buyers drive two-thirds of overall purchases. Casual e-book buyers “are not pulling their weight” compared with casual print book buyers, Gallagher said.
via E-Book Bummer: Growth Slower Than Thought—‘Incremental, Not Exponential’ | mocoNews.
Eoin Purcell's Blog 
Hi Eoin,
I’m skeptical.
I read this article yesterday and a number of things confused me. First of all, what *exactly* are they measuring that is the subject of slower than expected growth? The way the article is written, the cause of the disappointment appears to be the slower than expected growth in “the number of book buyers who also purchased an e-book.”
Excuse me? That sounds like they are asking print book buyers if they also bought e-books, right? How useful is that number really? Does it really tell us anything?
Unfortunately, there is no link to the original survery so we can’t check if this characterisation is correct. And on the Bowker/BISG sites, there is only a link to this article.
I’m pretty sure how they conducted the survey, though. Rather than questioning a random sample of the population Bowker/BISG tend to survey a self-selected reader panel. Why is this a problem?
Let me explain why I don’t think this panel is representative of the book buying population. According to their own figures (the Bookstats report, released in August), e-books captured approximately 8% of the market in 2010. However, again according to their own figures, the readers’ panel’s e-book purchases only comprised 2.2% of their total in 2010.
I wouldn’t feel comfortable making any statement about the market based on a sample population which seems to have pegged digital penetration quite a bit on the low side.
As a contrast, here are some numbers I would have a little more confidence in. Pew surveyed a random selection of the US population at the start of December 2011 and again at the start of January 2012. They had one simple question: do you own an e-reader or tablet?
They found that both e-reader and tablet ownership almost doubled in the space of a month.
It doesn’t sound like anything is slowing down to me.
Dave
A tour de force of meaningless statistics being used to support vacuous conclusions.