GalleyCat reader Sheila Gaines raises a good point about one of the blog's recurring themes, the monthly posts on book sales statistics. "When you say book sales have increased in 2007 you might want to state how that number came about," she emails. "Publishers have increased prices over the years due to reduced volume sales and the those price increases account for a percentage of the increase in sales."

"Some readers might confuse volume of units with increase in sales," she continues, "when in fact the same or reduced number of units have been sold. Increased sales in the book business does not necessarily mean more people are reading. If ten cars sold for $10 [each] in 2006, but eight cars sold for $13 [each] in 2007 would there be an increase in sales? Depends on how you look at it. The sales figures you have quoted also do not include returns."

So, absolutely, keep that in mind as the numbers from the AAP and the Census Bureau keep coming out: We're only talking about how much money's being made, not how many units are shifting.