The Positive Review Bias

Before I purchase a new book, I generally like to read a few reviews online.  Occasionally, the reviews I read are written by bloggers that I don’t know and other times they are written by professional critics.  As of late, I’ve been thinking about my own book reviewing process on this blog and all the sudden it dawned on me that relying on bloggers for objective book reviews is probably not such a good idea. The reason is that there is selection bias at play here.

Are there any incentives for bloggers to write a negative review of a book (or really anything) online?  I don’t think so.  In fact, bloggers (myself included) are incentivized to do the opposite. The reasons, I think, are twofold: financial incentives and social currency. Let’s examine those reasons.

Many bloggers write reviews for books with hopes of capturing affiliate commissions on the links provided in their reviews.  I certainly do this and I make it explicitly clear to readers that I do this.  I’ll take this opportunity to reiterate something I think is very important though, i.e., I never write a positive review for a book that I didn’t like (I’ve actually been approached by people to promote books on this site, but I refuse to do it if I don’t like it, even if I could potentially make money from it).

However, it’s certainly nice to make a few bucks (for more books and coffee), especially if you’ve exerted the effort to write a thoughtful review of a book.  This creates a conundrum for the ethical blogger though.  If one writes a positive book review there is the opportunity to make affiliate commissions. However, if one writes a negative review (and does it well), then there is no way anyone will buy the book through an affiliate link in the post.  The bottom-line, then, is this: there is clearly a financial incentive, for both ethical and unethical bloggers alike, to focus on positively reviewing books on their blogs versus critiquing books they don’t like.

The second reason that there is a bias to review books positively comes in the form of social currency, which is obviously a non-financial incentive.  Although, social currency can often be used as a tool to help improve one’s financial situation too and that factor shouldn’t be downplayed either. OK, so gaining social currency in the blogosphere (or even amongst real-life peers) is obviously important for many reasons, namely that gaining approval from the right folks can open the door to many exciting and unique opportunities that offer both financial and non-financial rewards. Kissing someone’s ass by writing about how much you love their work is one way to gain social currency, or it may just make you a sycophant.

Reviewing a book negatively on a blog, however, will rarely gain one social currency though. In fact, I’d go so far as to say that there is actually an incentive to avoid reviewing books negatively. This is because authors don’t want negative reviews out there. Accordingly, a harsh critique is more likely to draw negative attention and vitriolic attacks from the author (e.g., check out this review where Alain de Botton lost his composure in the comments section). Even professional critics are at least subconsciously thinking about social currency. I will concede, however, that in some circles (particularly among professional critics) critiquing some books harshly will actually provide you with more social currency.


Let’s use Coffee Theory as an anecdote.  I’ve written exactly one entirely negative review and this was mainly just to prove to myself that I was capable of writing a critical review. Since I’m not paid to objectively review books on this blog, there is very little incentive for me to review books negatively. If I read a bad book (or put a book down before finishing it) I usually give it one or two stars on Goodreads and then forget about it. However, I think this is potentially a disservice to fellow Web surfers and blog readers. Since I decide not to review these books, my reviews obviously never show up in a Google search result.  I also suspect that most bloggers think like this as well and thus there is likely to be an abundance of positive reviews online and not enough negative ones. Therefore, when I go searching for reviews of new books I’m more likely to find positive reviews, regardless of the book’s quality!

We don’t generally tip people for helping us to avoid bad books, but perhaps we should.  Negative reviews, in many instances, might ironically be more valuable than positive reviews. The reason, of course, meshes with a recent theme on this blog, i.e., we mistakenly overvalue positive advice and undervalue negative advice.  As for this blog, you’ve been warned that there is a bias towards positively reviewing books (etc.) here. In the past, I’ve really only reviewed books I like and this trend will mostly continue going forward. Accordingly, I can only hope that you like my reviews, err, I mean recommendations.