Of book reviews and selection bias

Publishers send me books to review. I guess I’m on the list of potential reviewers, which is cool because I often enjoy reading books. And, even if I don’t get much out of a book myself, I can give it to students. A book is a great incentive/reward for class participation. For any book, if you have a roomfull of students, there will just about always be somebody who’s interested in the topic.

Anyway, most of the time I don’t write or publish any review, either because I don’t have anything to say, or I don’t find the book interesting, or because I think I’m too far from the intended audience, or sometimes just because I don’t get around to reviewing it—this happens even for books I really like.

The other day I received a book in the mail on a topic that does not fascinate me, but I took a look anyway. The book was boring—even given his topic. The book had some historical content which seemed unbalanced (too much focus on recent events and a shallow, episodic treatment of what came before), also it had what seemed to me to be a smug tone—not that the author seemed like a bad person, exactly, just a bit too complacent. I just didn’t like the book, enough so that I didn’t even give it to a student, I just set it outside somewhere for some stranger to read.

I forgot about this book entirely, and then I happened to be looking at a blog post by someone else who, like me, receives a lot of books from publishers, reads a lot of books, and reviews a lot of books. He reviews more than I do, actually, often quick one-paragraph blurbs. And I noticed that he mentioned this book! I was surprised: did this blogger actually like that book? Maybe not: it’s not actually clear, as his one-paragraph review was descriptive but not actually complimentary.

Anyway, this brings us to selection bias. Most of my book reviews are positive. Why? For one thing, when I don’t like a book, often it’s on a topic I don’t care about and don’t know much about, so I’m not so interested in writing a review and I don’t feel so competent to write one either. Also, when I get a book for free, I guess I feel like I owe something to the publisher.

I do sometimes write negative reviews of books I receive for free, but there’s some selection bias here.

The funny thing is, I often write negative reviews of journal articles that people send to me. Why is that different? For one thing, books are usually sent to me by their authors or publishers, whereas I’ll often hear about a journal articles from a third party who already doesn’t like the article. Also an article is typically making a smaller, more specific point, so it makes more sense to criticize it on specific grounds.