That question can not be answered with the information presented in the article. Most interesting questions can't be answered with the information presented in

That question can not be answered with the information presented in the article. Most interesting questions can't be answered with the information presented in the article. Bookscan doesn't measure usage of programming languages. Bookscan doesn't measure demand of programming language books. The best it can do is measure publisher efficiency at predicting what might sell--and O'Reilly doesn't even give the necessary information to show that. Most tech books have a maximum shelf half-life of eight months, and of course once a book is off the shelves, it's really hard for Bookscan to measure its sales.